CQ-TV 185 Magazine

Contents

Contents...... 1 Committee Contacts...... 2 Editorial ...... 3 An Introduction to Test Card ‘M’...... 4 ATV Contest Records...... 6 CQ-TV Commercial advertising rates...... 7 Sales of the Century...... 8 TV on the Air ...... 10 12GHz Prescaler ...... 11 Experimenting with Video - part 2 ...... 14 Simple TV Repeater Ident and Controller...... 19 Recreating the Cambridge Studio...... 20 A tribute to Barry Keedy, G6LIC ...... 21 Tuneable TX for 23 and 13cm...... 22 Deadline...... 28 Satellite TV News...... 30 Micro transmitters...... 32 Digital Terrestrial TV Arrives in the UK ...... 33 BATC Publications...... 35 Members’ Services ...... 36 The Empire Strikes Back! ...... 39 Oscillators Using Logic Gates ...... 42 Shuttleworth 99...... 44 Photo Gallery...... 45 Accuracy of Recovered H. P. 478A Thermistor Power Sensing Units...... 47 Circuit Notebook No. 66 ...... 48 BBS Closure...... 48 TELETEXT Pattern Generator Improvements...... 49 Digital-ATV - today and tomorrow...... 51 Historical Achievement for Amateur Radio and the Mir Space Station!...... 53 Post and News...... 54 Members adverts...... 55 Index of Advertisers...... 56 Edited by Ian Pawson, circuits drawn by Allan Robinson, proof read by Peter Delaney. All rights reserved, all wrongs denied. Legal Niceties E&OE. Whilst every care is taken in the production of this publication, the editor accepts no legal responsibility for the advice, data and opinions expressed. The BATC neither endorses nor is it responsible for the content of advertisements or the activities of those advertisers. No guarantee of accuracy is implied or given for the material herein. The BATC expressly disclaims all liability to any person in respect of anything and in respect of the consequences of anything done or omitted to be done wholly or partly in reliance upon the whole or any part of this magazine. The contents of this publication are covered by international copyright and must not be reproduced without permission, although an exception is made for not-for-profit publications (only) wishing to reprint short extracts or single articles and then only if acknowledgement is given to CQ-TV. Apart from any fair dealing for the purposes of published review, private study or research permitted under applicable copyright legislation, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopy, recording or otherwise, without the prior permission of the publisher. All copyrights and trademarks mentioned in this publication are acknowledged and no infringement of the intellectual copyright of others is intended. Printed in Great Britain. Copyright © 1999 by the BATC and contributors. Notice to Contributors Authors are alone responsible for the content of their articles, including factual and legal accuracy, and opinions expressed by them may not reflect the editorial stance of the publication. Material submitted to CQ-TV should not infringe the copyright of other writers or bodies. Articles remain the copyright of their authors and following publication in CQ-TV, they may also appear on the BATC's web site and CD-ROMs, also in other not-for-profit amateur publications. Contributions are accepted for publication on this basis alone.

BATC Chairman: Trevor Brown G8CJS Club affairs, Video tape library, Technical queries, especially relating to handbook projects. 14 Stairfoot Close, Adel, Leeds, LS16 8JR. Tel: 01132 670115. E-mail: [email protected]

BATC General Secretary: Paul Marshall G8MJW General club correspondence and business. Library queries relating to the borrowing or donation of written material. Fern House, Church Road, Harby, Notts., NG23 7ED. Tel: 01522 703348. Email [email protected]

BATC Hon. Treasurer: Brian Summers G8CQS Enquiries regarding club finances, Donations, and constitutional enquiries. 9 Prior Croft Close, Camberley, Surrey, GU15 1DE. Tel: 01276 677879, Mobile 0850 014892 Email: [email protected]

CQ-TV Magazine: Editor Ian Pawson Anything for publication in CQ-TV, Articles, Review items, Letters to the editor, and other material except as below. 14 Lilac Avenue, Leicester, LE5 1FN, England. Tel: 0116 276 9425, Email: [email protected] Photographs for the CQ-TV covers: - Please send any photographs by post, electronic images by email, to the editor at the above addresses. TV on the Air: - Graham Hankins G8EMX, 11 Cottesbrook Road, Acocks Green, Birmingham, B27 6LE. Tel: 0121 707 4337 Satellite TV News: - Paul Holland G3TZO, Chatterton, Chapel Lane, Threapwood, Nr. Malpas, Cheshire, SY14 7AX. Tel: 01948 770429, Email: [email protected] CQ-TV Advertising Manager: - Chris Smith G1FEF 25 Dando Close, Wollaston, Northants, NN29 7QB. Tel: 01933 666979 Fax: 01933 666972. Email: [email protected] CQ-TV Awards: - Bob Webb G8VBA, 78 Station Road, Rolleston on Dove, Burton on Trent, Staffs., DE13 9AB. Tel: 01283 814582

Exhibitions Mike Wooding G6IQM, 5 Ware Orchard, Barby, Nr. Rugby, CV33 8UF. Tel: 01788 890365, Fax: 01788 891883, Mobile: 0860 857434 Email: [email protected]

Club Sales Members Services: - PCB’s, components, camera tubes, accessories, etc. (NOT PUBLICATIONS). Peter Delaney G8KZG, 6 East View Close, Wargrave, Berkshire, RG10 8BJ. Tel: 0118 940 3121 Publications: - Handbooks, Back copies CQ-TV, and anything related to the supply of BATC publications. Paul Marshall, Fern House, Church Road, Harby, Notts., NG23 7ED, England. E-mail: [email protected]

Membership Anything to do with membership, including new applications, queries about new and existing membership, non- receipt of CQ-TV, subscriptions, membership records, data protection act. Dave Lawton G0ANO, ‘Grenehurst’, Pinewood Road, High Wycombe, Bucks., HP12 4DD. Tel: 01494 528899. E-mail: [email protected] Club Liaison: - And anything of a political nature, co-ordination of ATV repeater licences. Graham Shirville G3VZV, The Hill Farm, Potsgrove, Milton Keynes, Bucks., MK17 9HF. Tel: 01525 290343. E-mail [email protected] Contests:- Richard Guttridge G4YTV, Ivy House, Rise Road, Skirlaugh, Hull, HU11 5BH. Tel: 01964 562498 BATC BBS Sysop: - Brian Kelly GW6BWX, 12 Cotswold Way, Risca, Gwent, NP1 6QT. Tel: 0410 279606. E- mail: [email protected] Please note that the BBS has now been permanently closed down. Repeater Liaison: - General enquiries and repeater affiliation. Graham Hankins G8EMX, 11 Cottesbrook Road, Acocks Green, Birmingham, B27 6LE. Tel: 0121 707 4337.

BATC web master Anything to do with the BATCs web site. E-mail: [email protected]

Welcome to the 50th year of the BATC members a week joining as our older members will realise there via the internet. If you are has been a lot of changes in the past 50 not connected to the years and another one is about to take Internet but have a PC you place we have now produced the first can still see our site by ever A4 CQ-TV. We talked about it, purchasing the club CD. we asked the membership what they This has also undergone wanted, we asked the printer what it some changes in that all would cost to produce and then the files have been locked eventually its crunch time and a to prevent the copy being decision has to be made perhaps one of edited. This was a request the most difficult decision the from one of our committee and I have been part of. The contributors and one that membership input was to stay A5, but we are happy to comply there again there was less than 1% of with, the pages can still be the members that replied. The printer printed out, this function said it would cost no more to produce has not been inhibited. 48 pages of A4 than 96 pages of A5, it would give use head room to produce This year is also a BGM more pages if we ever needed to as 96 year and the BATC’s 50th pages is the limit of a staple binding. Anniversary year, to mark Last but not least we have to think this we are organising a gala event, And, sent in by Andrew Emmereson:- about our editor, he has been wrestling award ceremony and combined BGM, with the software from the start, its all as always we are anxious to have your "Someone noticed then"... designed for A4 and actually produces input as to what you would like to see A4 pages with the A5 copy compressed or include in the event. Paul Marshall I always like to see the oddities at IBC, to the central area. With all the other and myself are doing the organising, even if (as with the Dutch bulb and ATV magazines producing A4 the date and time have been set for clog stands) they look like booth spaces magazines any subsequent reprints August 8th at Shuttlworth College part that nobody else wanted to buy. In the have been re-drafted by Alan Robinson, of Cranfield University Nr. Bedford 'new technology campus' on a stand run to fit our compressed format. So the remember the Cat 94 venue, apologies by the British Amateur Television inevitable change has happened we in advance if this interferes with your Club, there was a demonstration of the moved to A4 as we moved from 405 to family holiday, but for this popular original Baird 30-line television from 625 at least in the UK, we moved from venue it was the only available date. the 1930s. Now I know I shouldn't say AM to FM and so far I think you would this but it seemed to my weary eyes (on my last day in Amsterdam) to be a little all agree we got it right lets hope this I am going to close with another better than many MPEG systems at the also applies to our new magazine obituary of one of our members. On show. -- From the Editorial of the format. October 8th Robert Atkinson G3PUU December 1998 issue of International passed away. He was a member and life Broadcast Engineer magazine. Well Other changes have been taking place long friend to my family and me, done Grant! around us - the 10GHz allocation for without his help I doubt if I would have example. We are also being asked by ever mastered Television engineering. the Data Communications Committee It was only a few weeks before he died to furnish proof that the ATV on 70cms that we were sat down at his kitchen is ACTUALLY BEING USED BY table puzzling our way through the ATVers! We need evidence of 24cms/13cms ATV transmitter in the photocopied logbooks, worn out Dutch magazine Repeater, as a result I feel that I have been instrumental in 4CX250B's etc. Graham, G3VZV, will the circuit and translated text is this change in size of CQ-TV, but, as be assembling our response so please reproduced in this magazine. Trevor has mentioned, modern forward the data to him at the address software is geared to the A4 size. I have tried several desktop publishing on page 2. It is now “Use it (and prove Let me finish on a positive note I hope packages in the last few months but it) or lose it”. you will all sit back and enjoy the first they all favour the A4 page size. I hope A4 CQ-TV, it is something of a that this issue does not disappoint any Our website is also growing and we landmark to start 1999 with a whole ew of you too much. If you have any have just had the annual bill from look magazine and I hope you will helpful comments, then please let me Clearlight, it does not seem a year since enjoy it as much as you have enjoyed know. My contact details can be found we took out domain registration and the last 184 magazines in A5 format. on the committee contacts page above. http://www.batc.org.uk became a Let me wish you all a Belated Happy reality. The number of hits often runs at New Year to each and everyone of you. 1,900 per week and come from all over Ian Pawson, editor CQ-TV. the world often resulting in 2 to 3 new Trevor Brown BATC Chairman

Test Card M is a DTI funded need them. The programme is led by collaborative project under the Digital UK TV equipment manufacturer Snell Test Bed programme between Snell & & Wilcox, who are responsible for Wilcox, the BBC, the ITC, Channel 4 identifying the requirements of the test and the ITVA. card as well as creation of the digital sequences that will be used. By now the world is becoming familiar with the Test Card ‘M’ image, but what The programme is supported by all the is behind that image, and how does it UK free to air broadcasters (BBC, ITV, reflect the needs of the bright new Channel 4) and the ITC (Independent transmission is characterised by its digital age? Television Commission). They ability to appear perfect even in the consider that, without such test presence of errors or poor delivery Test Card ‘M’ is a sort of carrier – a sequences, a fragmentation of standards channels right up to the point where container full of digital tests that can in the broadcast industry may be errors become too hard to conceal or exercise and prove all the different unavoidable, and there will be no correct, at which point the transmission aspects of digital TV delivery, from guarantee that viewers will receive fails completely. This is a “cliff-edge” video and audio performance right satisfactory service from digital effect, and makes it very hard to through to the multiplex structure. The television. anticipate when there is a problem until visual image is the public face of the it causes a complete break down. The test card. Behind this image is a raft of The programme has already produced corollary to this, of course, is that a different bit sequences and structures, the first release of test sequences, and viewer using a digital television each of which tests a different aspect of the requirements capture process is receiver will not notice any degradation the digital delivery chain. underway, in which the needs of in the service when reception broadcasters, multiplex operators, conditions are varying until the signal fails – the service is either there or it isn’t!

The task of a test card, then, is to show what is going on in the delivery chain in a way which is easy and quick to use and unambiguous in operation. It needs to be able to show how near to the edge the service is operating, so that the effect of changes or degradations in the delivery conditions can be assessed before they become critical. Use of the test card is not limited to monitoring in-service delivery by broadcasters (indeed, the current analogue The “Cliff Edge Effect” – a viewer’s perspective! service no longer transmits a test card, and when full 24 The Test Card ‘M’ programme was transmission operators and receiver hour operation is launched in the UK, with support from manufacturers are being collected to established it is unlikely that digital the UK DTI, to create a “test card” for ensure that the test sequences are as services will either). Set-top box digital television. The work being universally applicable as possible. manufacturers and digital TV performed on this programme will equipment manufacturers will need to ensure that simple to use, intuitive tests test the operation of their product using are available when digital television The need for a digital Test Card a recognised industry yard-stick, just as installations and first transmissions Unlike analogue service, digital the multiplex operators will wish to test

Page 4 CQ-TV 185 © 1999 by the BATC and monitor the complete broadcast of elements that can be seen to be the compliancy needs of the relevant chain. Test Card ‘M’ will provide moving (such as the rolling cube, specifications. Once the equipment has universally accepted test bit-streams rotating colour phase, rotating clock been tested against a compliance that can be used to give providers and hand and synch meters), to demonstrate specification that invokes Test Card regulators the confidence they need that that decoding is continuing (and the ‘M’ it can be certified in a certification the viewers are getting (and will decoder has not crashed or “frozen”). document as having conformed to the continue to get) the best possible specifications. Test Card ‘M’ has been service out of digital TV. Other, more specific screens exist for accepted as one of the test certain functional tests, which are methodologies that will be specified by characterised as video tests (VID), DTG in the UK to show How Test Card ‘M’ is designed audio tests (AUD), data tests (DAT) or interoperability of the components of to be used multiplex tests (MUX). The severity of Although a digital television the test (or stress level) is transmission is made up of more than indicated by the final letter of the just audio and video, these are still the identifier, where ‘a’ means ‘easy’, easiest formats to use to try to see ‘c’ means ‘just at the maximum quickly what is happening. It is easier without being illegal’, ‘x’ means to “see” or “hear” an effect than to ‘illegal’ (in the DVB sense) and deduce subtle multiplexing effects from ‘b’ means ‘somewhere between ‘a’ a string of numbers! The “Cliff Edge and ‘c’. Of course, a test that is Effect” diagram on the previous page very easy for a video decoder may gives an illustrative idea of what is be very difficult for the multiplex, happening in the transmitted multiplex. so this definition only applies to the element defined for that test. The Video and Audio content are easy This unique identifier is essential to see on a monitor or standard TV for showing which test is being receiver, but are only one component of performed since the same video the multiplex, which also carries other screen may be used for a number services, data and all the housekeeping of different test sequences. needed to make the multiplex work. This multiplex is encoded into a The role of Test Card ‘M’ in COFDM format for transmission, which is itself carried as an RF signal Conformance, Compliance from the transmitter. Test Card ‘M’ and Certification does not test either the RF transmission Conformance, compliance and or the COFDM encoding, neither does certification could be called the it test the compression or encoding three “C” words of testing. They process, since these are proprietary and are what users and manufacturers can be carried out in any way which is of digital TV equipment will want compatible with the DVB standards. to do, and they want to know how The Pyramid of Content in a Digital The test card is designed in such a way Test Card ‘M’ will help them to do TV Transmission that it uses the video and audio to it. Because of the complexities and indicate the health of the entire the evolving nature of digital the digital television system. multiplex layer. This is done by transmission, it is not possible to create “stressing” individual multiplex a definitive “conformance” test, since it parameters, and using the video to is impossible (given a finite testing The Continuing Development of indicate whereabouts in this sequence time) to provide an exhaustive test of Test Card ‘M’ the test has reached. If the delivery all elements of the MPEG, DVB and The test card project has now released chain or decoding fails at any point in DTG specifications. Nonetheless, the first CD-ROM of test sequences, the stress cycle, then it is clear from the although it will never be possible to which are available on a commercial video what that level of stress actually definitively prove that a piece of basis from Snell & Wilcox. The work was. A typical video screen from the equipment is conformant with all the of specifying and producing other test Test Card ‘M’ suite is shown below. specifications, it will be possible to sequences, which will extend the range This is the most familiar image of Test show if the equipment is non- of tests available, is continuing, and Card ‘M’, and is used for video conformant in some way, and where will lead to further test card releases decoding and display performance, that non-conformance lies. The use of over the course of the next 12 months. audio/video synchronisation and Test Card ‘M’ can then be incorporated As time goes on so more and more video/sub-title synchronisation. into compliance testing, by which an users are adopting Test Card ‘M’ as an equipment or equipment chain which aid to conformance. Test Card ‘M’ is Traditional line-up elements are supports and displays the Test Card being established as the principal included, since this is a video test ‘M’ bit-stream correctly can be deemed benchmark against which transmissions (indicated by the VID part of the to be compliant with the test and receivers need to be validated. As identifier), but of course this is a specification. It is the role of Test Card the horizontal digital television market moving image, and contains a number ‘M’ to ensure that it reflects accurately develops, the use of this common

© 1999 by the BATC CQ-TV 185 Page 5 measurement yardstick will ensure that will be as universally applicable as Card ‘M’, visit the web-site at continued interoperability of all possible. www.snellwilcox.com elements of the delivery and receiver chain can be achieved. Snell & Wilcox is a world leader in the Or contact Paul Walland at design and manufacture of digital [email protected] image processing products for Snell & Wilcox Heads up UK television broadcast and post Snell & Wilcox Ltd, Durford Mill, Digital Test Card Program production applications. The company Petersfield, Hampshire GU31 5AZ, Snell & Wilcox have been chosen to has won many awards for its innovation UK. Tel: +44(0) 1730 821188, Fax: direct the recently launched programme and engineering excellence including +44(0) 1730 821199 to create a “test card” for the UK’s five Queen’s Awards for Industry, two digital television broadcasts. Emmy awards from the National Snell & Wilcox Inc., 1156 Aster Academy of Television Arts and Avenue, Suite F, Sunnyvale, CA, The first sample test sequences have Sciences and the European Information 94086, USA, Tel: +1 408 260 1000, already been produced, and the Technology Prize. Snell and Wilcox Fax: +1 408 260 2800 requirements capture process is under products are in use worldwide by many way, in which the needs of of the most prestigious broadcasting All images and text are copyright © by broadcasters, multiplex operators, and post facilities in the industry. Snell & Wilcox Ltd., and are transmission operators and receiver reproduced here with their kind manufactures are being canvassed to For further information on the permission. ensure that the test sequences created development and availability of Test ATV Contest Records

Here is the updated list of ATV and in English) encourage the ATV traffic and records. If you have some new details experimentation. or additional information, please let me Thank you for your co-operation in know at [email protected]. You helping me to maintain this list up-to- Michel Vonlanthen, HB9AFO, SWISS will find all details of each QSO, the date, for the full benefit of all ATV ATV President. chronology of all registered records and hams. Its goal is not to promote the methodology used at: competition itself and only but to http://www.cmo.ch/swissatv (in French

NEW DOVE TUNEABLE IF / RX KIT.

The Dove ATV Tuneable IF./ RX. forms the ideal heart of an ATV receiving system for either 24CMs (pre-amp recommended) or the higher bands when used in conjunction with a suitable Low Noise Block converter.

The flexible design concept allows for expansion to suit your needs for now and the future.

Easy to construct requiring no adjustment, setting up or alignment. The kit contains all board mounted components and full instructions.

Brief spec. Size.105mm wide x 97mm deep x 50mm high. Power. 12vDC @ 400mA. Frequency range. 925MHz - 1800MHz. Audio subcarrier. 6MHz. Video bandwidth. Variable.

Video outputs. 1v PK/PK + Base band. Audio output. 1.5Watts. Controls. (all 10K pots) Main tuning, Volume, Video gain, Video bandwidth. LNB power on/off switch.

DOVE RECEIVER KIT £42.00 all-inclusive. GUNNMOD2 3CMs ATV. TX. kit. Very popular full feature Gunn diode TX. Complete with pre-tuned oscillator head. £30.00. PCB. kit less oscillator head £20.00 3CMs LNB’s. All with 9GHz Local oscillators. New 0.7db nf. with dish feed horn. £43.00. With 22mm circular W/G input £45.00. Others and second hand units available. Please contact. WG16 to 22mm Circular transition. Converts 22mm circular to WG16 and vica verca. 24CMs LOW NOISE HIGH GAIN GASFET PRE-AMP kit. 40db gain 1db NF. band pass helical filtering. 12-18vDC feed via co-ax. Designed specifically for ATV. but good for all modes £60.00 DTMF DECODER kit. Very high quality decoder IC. All o/p’s buffered. Will directly drive TTL/CMOS or relays. Can be used to control whatever your imagination thinks of. £12.00 Prices are all inclusive of P&P etc. (+ 10% abroad) PCB’s are available assembled and tested at extra charge. SAE. (to take A4 paper) for further details or call. Orders and enquiries to:- BOB PLATTS G8OZP. 220 ROLLESTON ROAD. BURTON UPON TRENT. STAFFS. DE13 0AY. PHONE 01283 531443 7 - 9PM WEEKDAYS PLEASE

CQ-TV Commercial advertising rates

Size Mono Colour Quarter page £20 £25 Half page £40 £50 Full page £80 £100

Discounts of 5% for 2-3 insertions and 10% for 4 and above apply to the above prices.

If you would like to advertise in CQ-TV, then please contact our advertising manager, Chris Smith ( G1FEF ), 25 Dando Close, Wollaston, Northants, NN29 7QB. Email: [email protected]

By Dicky Howett cameras were dispatched to a TV held throughout three days in May station in Greece. Kit also found its 1993. Amongst the thousands of Lots Dicky Howett rummages in a few way to South America and New on offer, a studio-set of Hitachi 110 bargain basements and uncovers the Zealand. Some cameras even ended cameras, an AMS digital/stereo 48 busy world of video second-hand their days down the siding, shunting channel audio mixing desk (only used selling. with British Railways. The cameras for three programmes) and a white were installed in a studio presumably to Bosendorfer Grand Piano. The TSW Used, previously operated, second- teach B.R. staff the proper way to tell sale was a success, but apparently the hand. Whatever it’s called, good customers which train would not be weather influenced bids. Better prices quality TV broadcast equipment will arriving at which platform. Later, in were obtained on sunny days than on always find a market. 1969 when all-channel colour arrived, rainy days the ever-resourceful BBC sold some Whether it`s cameras, monitors, microphones or lights, they can be yours at a special price. Just ignore the scratches and don’t worry that the kit was probably once used on the ‘plane crash’ episode of ‘Emmerdale’! But who actually buys old TV kit and how does the business operate?

It’s been going on for years, (and not only Emmerdale). Surplus broadcast kit has always found its way into the public domain. In the 1960s the original commercial TV channel, Rediffusion, had four surplus American RCA TK11 monochrome 3” I.O. studio cameras stored in a basement room at Television House, Kingsway in London. Unfortunately the basement flooded and the cameras got wet. Undaunted, Rediffusion refurbished the four cameras (rugged valve types in those days) back to working condition and sent them to Yugoslavia to provide facilities for Yugoslavian Television after the 1963 Skopje earthquake. By Thames TV sale organiser Bob Warren. all accounts it was kit gratefully received. well-used Marconi Mk IV monochrome Also hitting the 1992 lost franchise fan cameras out of Television Centre to was Thames Television. During 1993, Australian TV. Australia didn’t Thames publicised several large sales The BBC also operated a second-hand colourise until 1975. The mono of broadcast equipment. One of the sell-through outlet. This was their cameras were used as a stopgap. But sales organisers was Thames engineer ‘Redundant Plant’, (of fond memory) you’ll be out of luck these days if you Bob Warren. He recalls, “Like most down at Power Road in Chiswick and it want to buy any ex-BBC equipment. other big broadcasters, Thames was stocked to the chocks with surplus The final sale was in April 1996 when Television habitually disposed of TV studio and o.b. equipment. Usually, the BBC’s redundant plant was itself redundant equipment, and we had our every ten years or so BBC Television made redundant. own Redundant Equipment Officer at re-equipped, which meant that there Teddington. By the end of 1991 we could be a small mountain of, used telly knew we’d had it as a broadcaster, and cameras to shift. (Once, a single buyer Closer to home, as a result of the great when the time came to sell the studio for £200 purchased eight Marconi Mk Tory inspired 1992 ITV franchise kit, we had two choices, either a great II’s the lot!). The BBC was quite debacle, several broadcasters found big auction like TSW or a sealed bid sanguine about this process and flogged themselves well and truly out on their with a reserve price system. We chose regularly its spare kit to grateful collective TV ear. Thus, big sales of the latter. We had several sales during recipients, (typically universities or TV kit were heralded. Down in the 1993. Our biggest sales were at our foreign TV stations) especially if they West Country at Plymouth, Television O.B. base at Hanworth and our London had ready cash. South West emptied the contents of it’s Derry’s Cross studio with the help of studios at Euston Road” Liverpool-based auctioneers Elston For example, during the nineteen Sutton. An ‘all comers’ auction was Typical Thames reserve prices sixties several cartloads of ex-BBC

Page 8 CQ-TV 185 © 1999 by the BATC throughout the sales were for the clients to donate. We always pass on Prior to working for D.S. Video following; an Acron 502 SPG (£300) requests like that and it is really up to Facilities, Martin Joannou worked at and some Ikegami HL95 cameras at our clients if they want to donate the BBC’s Redundant Plant. He knows £1,700 each. anything. We seem to get on quite well the business. Martin1 “We have in our with the main second hand dealers and warehouse currently everything that Bob Warren, “In 1993 we disposed of we often auction their own stock if it we’re advertising. Some firms don’t do our LDK 5 O.B. cameras priced at sticks on their shelves. Our last big this and will only buy to order. This we £1000 for all six. They went to BATC asset sale was for Central TV in do also. If, for example a customer members or people wanting souvenirs Birmingham where we auctioned edit wants a Vinten Osprey pedestal, I’ll of Thames. On the other hand, our suits, transmission equipment, film first ring Vintens, or check with our RCA TK47 studio cameras like competitors, or even ring my much totally obsolete and broadcaster contacts to see what valueless tv equipment went to they’ve got. Lately we’ve had a worthy causes and in this case as lot of enquiries from African a gift via the Foreign & broadcasters. For example they Commonwealth Office to will ask for a Beta SP system but Lithuania. Thames Television only want to pay about £500. In kept for a while, the three studios fact it turns out that all they at Teddington but the Hanworth really need is a low-band outfit, O.B. base was demolished and mainly because all the local now is home to a couple of village stations are low band superstores. The Euston Road anyway. Someone had sold them site has been re-developed but on the idea that the digital not as TV studios.” revolution is here, but it’s not. At least not for them”. Currently, the second hand market is serviced by a large Martin Joannou has to know his number of firms and individuals, way around the regulations working either as auction houses, concerning the export of goods. commissioned agents or able to Martin, “For export our usual provide an immediate choice system is that once the goods from stock. have been paid for and packed, if the customer is going to take the HENRY BUTCHER has been goods through customs as around for over 100 years. As personal luggage we insist they valuers and auctioneers, the complete two C.A.88 Customs company has been involved in forms. This form proves the goods are leaving the country the audio-visual industry for at Checking the Steenbecks. least twelve years. Associate legally and are VAT exempt. The partner Jeff Hill comments, “We transfer and studio kit. It’s all sold as only problem is that we have to at Butchers offer a whole range of seen. We don’t provide any warranties. spend time and send someone down to services but we only started auctioning Some of the equipment can be quite the departure point to retrieve the tv and audio kit about four years ago. old, especially tube tv cameras. The second copy once it has been stamped We have three primary means of previous Central sale offered ten by Customs. You can imagine the selling: By private treaty, tender or Hitachi SK11OA cameras that went for problems we can have without these auction. In fact our latest sale is by £150 each, mostly to individuals who I little forms. private treaty for a complete digital guess wanted them to play with. That post-production facility located in type of camera is of no use in The second hand market continues to Benelux.” production. In fact I heard recently that thrive. If you’re looking for a tie-clip some of those cameras are now used in microphone, a non-linear distortion Twelve years ago Butchers valued the a London pub as bar stools!” analyser, a Barco monitor or a mobile whole of HTV. Since then the company recording studio (ex-Rolling Stones has been involved in most major (and Down at Acton, D. S. (Dingle Star) 1979-one off) then raise your hand, some minor) asset sales. Jeff Hill, VIDEO FACILITIES can offer place your bids and pass the cash “Changes in TV technology will videotape recycling. Salesman Martin please. obviously imply redundant equipment Joannou, ‘We buy used Beta SP, clean somewhere. People who come to our it, erase it and evaluate it. The rest of For more information contact:- auctions are a very broad range, our business involves buying and ELSTON SUTTON & CO. 0151 255 dealers, end-users and people off the selling new and used broadcast 0951. street. The newer equipment tends to equipment. Big broadcasters or other HENRY BUTCHER. Jeff Hill. 0171 remain in this country, the older stuff dealers will offer us packages or we’ll 405 8411 ending up in the far-flung corners of go to sales. We give a warranty on all D..S. VIDEO FACILITIES. Martin Europe or even museums. Museums our stuff, in fact we can’t sell it without Joannou. 0181 965 8060 sometimes contact us to buy or ask our guarantees.

By Graham Hankins G8EMX. repeaters’ site is nearby Auckland’s on end, lifted vertically with shouts of main TV transmitting tower called “nearly there, now slide the BOLT!”. It’s been some while since TVOA has “Waiatarua”. Those in the “trade” The deed was done, the long pole mentioned the New Zealand scene, so I report using ZL1BQ as a good “weak” sections added and the Alford-Slot had better open with some recent E- signal for testing as its transmitter is raised triumphantly aloft. Was it too mails from Michael Sheffield ZL1ABS. 20dB less powerful than the weakest high for the conditions...we had no Mike tells me: “The ZL1BQ ATV commercial UHF TV transmitter. means to ‘guy’ it at the time. Well, it repeater in Auckland was still up there some (operated by the Auckland weeks later, so maybe ok! VHF Group Inc. branch I have particularly taken no66 of N.Z.A.R.T.) has pictures of the present had a facelift for the 1998 set-up, so please find Spring season (Southern some space, Ian! hemisphere) in New Zealand. The main callsign, A short TVOA this time. information & test card I would really like to hear video generator has been of, and publish here, expanded to produce 32 times and periods of pages (was 16). It is the simplex activity ie ATV design from the B.A.T.C.s’ ‘nets’ and any 70cm “ATV Compendium” book ATV activity, by Trevor Brown G8CJS, using the teletext chipset Invite to the Microwave SAA5020 & SAA5050. All Round Table, BT the old pages have been Research Labs, near refreshed with new Ipswich. formatting & updated texts. A host of new pages were I was invited by E-mail to designed by Grant give an ATV talk as part ZL1WTT & Ian ZL1VFO (with a little When they can get ZL1BQ well the others should be P5+. of the Lecture Stream at the Microwave technical support on programming the Round Table meeting, which meant a Teletext EPROM formats from Michael 5.30AM start from Birmingham on a The UK summer and autumn season ZL1ABS) using graphical images & Sunday morning! flashing text headings. Quentin ZL1QF lived up to usual expectations, I think modified the microprocessor software October became the windiest and I was timetabled as ‘first on’ so & hardware in the repeater controller to wettest on record. So ideal conditions, delivered my usual overhead slides and handle the automatic page cycling of a really, in which the Beacons Repeater 35mm projections to a satisfactorily larger EPROM. Almost all facets of Group decided to raise the height of the large audience. The chairman kept the Amateur Radio, as well as ATV, get a Alford-Slot antenna for their 24cm programme strictly to time, so an hour “page” explaining their particular ATV repeater. flashed by. I always begin with 70cm, mode. Since the repeater beacons these then 24cm, and repeaters. pages 24 hours a day, apart from when With a near-gale already blowing, and Unfortunately there was no space for an ATV QSO is in progress, there is a rain likely, Alan Kendal G6WJJ and my video of repeater test cards, but I good opportunity to recruit viewers to Graham Hankins G8EMX carried two, was at least able to put ATV on the the hobby”. 3 metre triangular mast sections, a 6 agenda. metre length of pole, and a telescopic The New Zealand ATV repeater output mast just in case, up to the site for the On the ground floor, traders were frequency allocation (614 to 622 MHz) proposed repeater. The first 3-metre selling microwave ‘bits’ and a affords easy reception on any TV or mast was quickly bolted to a concrete ‘microwave clinic’ was handling a VCR equipped with a UHF tuner and base, then secured to the adjacent radio veritable queue of amateurs wanting UHF aerial. Whilst the major hut. The tricky bit would be to lift the their transmitters and receivers testing. broadcasters in New Zealand use VHF second 3-metre mast onto the top of the One pair had brought along a home- low band (45 to 68 MHz) and VHF first.] brew dual Alford-Slot, which they had high band (170 to 220 MHz) there is a meticulously machined from reliable, pay TV network and low power Who dares, wins (sometimes). Would published dimensions. What would its regional community stations on UHF we win? Well, Alan was going to do performance be like? Unfortunately, band (550 to 800 MHz). Many people the lifting and bolting, Graham would they E-mailed me a few days later, that have installed UHF aerials to receive add stability and positive comments their home-brew slot had been a failure, these commercial transmissions with from the top of a scaffold tower! With but that they would be going ‘back to the resulting bonus of reception of the dark clouds now racing across the the drawing board’. Better luck next Amateur station ZL1BQ. The heavens, the second mast was heaved time, gents!

By David Wrigley, G6GXK frequency counter. The box was formed work such as this. These are useful from 0.5mm tinplate. devices and are strongly recommended. Background and design aspects The LM78M05CV regulator had to be Since starting to construct microwave This unit is a practical way of used because the high current taken by units the author has made himself a low extending the range of a 1.5GHz the prescaler chip couldn’t be supplied electrostatic field assembly area which frequency counter It uses the Fujitsu from the frequency counter’s internal consists of a sheet of 0.5mm tinplate FMM110VJ chip to divide the input regulator. It should be noted that the over the working surface, with wires frequency down by a factor of eight. Fujitsu chip gets fairly hot when in use soldered to it, to the earthing point of a Working over the frequency range of – it is dissipating around 0.65 Watts in low voltage temperature controlled approximately 1 to 12 GHz, it was built that tiny case. For this reason and in soldering iron and to a wrist strap. This to fit directly onto the input socket of order to obtain good grounding it is was used to assemble the unit and has an inexpensive frequency counter, wise to ensure that it is soldered down been used successfully in the past to successfully extending its range up to to the PCB and that both sides of the assemble discrete GaAs FET devices. 12GHz. PCB are soldered to the tinplate box. Of course, modern IC’s are The regulator chip will also get hot, tremendously robust but it isn’t wise to especially if it is fed from 10 volts take unnecessary risks. or more, so it is best to mount it on the tinplate box. The prototype had its regulator bolted to a piece of Mounting the Fujitsu Integrated tinplate soldered across the back Circuit of the box. The first component to be mounted onto the PCB was the IC package. It Construction should be noted that the Fujitsu IC package is very small and the The PCB is small and simple connections are very close to adjacent enough to be cut with a modellers connections and also to the case, which Fig 2, PCB artwork knife if an etching facility is not to is ground. It is very easy to bridge these hand. There should be nothing connections with solder, or by poor The circuit (fig.1) follows that shown very critical about the tracks provided alignment to the wrong part of the in the Fujitsu data sheet for test the basic layout is followed. Drilling PCB, either of which would of course purposes and a decision made at the the PCB was accomplished by hand prevent the chip from working. The outset was that no exotic components using a 0.8mm PCB drill (ex-radio important points are:- would be used if they could be avoided. rally) mounted in the chuck of a pin All the other components were in fact vice. With a sharp drill this is a speedy Mount the PCB in a small vice or other SMD’s salvaged from old LNB’s or process. holding device to keep it steady. other microwave boards. They were all examined for good solder connections The author’s eyesight is not as good as Try the IC in place and make sure that and checked for value prior to fitting. it used to be and he has found it the IC connections, which go under the New SMD’s can be obtained from necessary to use a headband mounted IC package, are clear of other tracks. Maplin in 25-off minimum quantities. binocular magnifier to carry out fine The circuit is laid out on a tiny PCB using ordinary glass fibre insulated 0.1µF TANT + double sided copper clad board about + 1.5 mm thick. The PCB layout is DC SUPPLY shown in figure 2 at four times full size Fig 1. The circuit (actual length 30mm). The back plane 0.33µF TANT L78M05CV - is almost all copper with only diagram + 5V REGULATOR clearances being required for the 5volt 1nF link and connection – these can be cleared with a drill – the backplane doesn’t need to be etched. It was decided to put in four link pins using INPUT 51R OUTPUT short lengths of wire to bond the earthy 1nF 1nF parts of the component side to the backplane as in good microwave practice. FUJITSU 1nF FMM110VJ 10 GHz PRESCALER The overall assembly can be seen in 51R 51R figure 3 and is governed mainly by the DAVID WRIGLEY - G6GXK 1998 JUN 14 size of the BNC connector to the

© 1999 by the BATC CQ-TV 185 Page 11 Tin both the underside of the IC that the IC doesn’t move out of across the box so that the leads of the package and the PCB area and alignment during this part. regulator were close to the feed- connections leaving the minimum of through cap. and the 5volt connection solder on the PCB. Use solder wick to The pin connections can now be to the PCB. It is important to fit the remove any excess. completed using very fine cored solder 0.1uF capacitor across the input to the wire and with the iron away from the Regulator – otherwise it may oscillate. Use a clean finely pointed temperature IC to avoid bridging. Use solder wick It was soldered directly across the controlled soldering iron with the to clear away excess solder if things go regulator leads. The output of the minimum of solder on the tip. wrong regulator goes to the 5volt input and this is then linked across the back of the Hold the IC in place with tweezers, After successfully mounting the Fujitsu PCB to the other 5volt point. A view of carefully aligning all the pins and IC, the rest of the components can be the completed unit with its lid off is gently dab one of the ground pins to mounted, along with the wire links. The shown in Figure 4. attach it to the pcb at it’s tip, you will PCB is then soldered into the tinplate

Fig 3, Assembly drawing find the top left one is the most box, constructed in the same style as convenient in the long run. This will TV tuner unit, with lids either side. Testing locate the IC and minimise (For source of tinplate see ref. 3) The unit is very easy to test. Firstly misalignment whilst giving sufficient spend some time checking visually the flexibility to enable the underside of its soldered connections. Apply power and body to be soldered down. Completing the assembly check current consumption (about 130 The DC supply is fed through a 1nF mA). With no input there will be a high Hold the iron close to the chip touching feed-through capacitor soldered into the level of output at about 870 MHz. This the PCB and the two ground pins which tinplate wall alongside this the return is because the chip oscillates when not are together at the bottom of the IC so lead is soldered to a bent up 6BA solder driven and this is normal - just that the heat will melt the solder under tag soldered to the tinplate wall. At the remember that if you think that you are the chip. Press it down with tweezers back of the PCB the regulator was seeing 6GHz or so - it may be because when the solder is melted and hold for bolted with cut down leads (4mm) to a the output has fallen to too low a level a few seconds until set. It is important piece of tinplate which was soldered to trigger the prescaler. Find a source of RF at a level of about 1mW and frequency of 800MHz or more. Apply this to the input and check the counter. It should work without any problem, giving a reading of one eighth of the input frequency. It should also be checked using a 10GHz source such as a Gunn diode. For measurements like this, one useful technique is to feed the prescaler from an SMA to waveguide transition and a small diecast horn. This can then be pointed at the end of a waveguide or at a horn feed and adjusted until a good steady reading is obtained.

Conclusions Fig 4, A view with the lid off Overall a very satisfying project, which continues to prove its worth on a daily

Page 12 CQ-TV 185 © 1999 by the BATC basis. 2, You need a calculator to multiply the source that will be locked against a result by 8, not quite as convenient as a 10MHz or so Xtal oscillator. Two prototypes have been built so far direct reading device. There is no easy with a third one in process. No solution unless the counter you use has Ref .1, A 12GHZ Prescaler 1:8.by problems have been experienced in provision for prescaler multiples to be Angel Vilaseca, HB9SLV and Serge their construction or operation. input. Any other solution would either Riviere, F1JSR, DUBUS TECHNIK IV require extensive modification to the 1995. There are some limitations and possible counter or a worsened resolution. improvements. Ref. 2, Fujitsu Microelectronics Ltd, 3. The power-input limitations could be Compound Semiconductor Division, 1. It needs to remembered that a strong improved by using an input buffer Network House, Norreys Drive, reading of about 870MHz (6900MHz) amplifier that could both improve Maidenhead, Berkshire, SL6 4FJ. Tel will most likely be a “no signal” or sensitivity and provide some limiting 01628 504800, Fax: 01628 504888. “low signal” input condition. As the against higher powers. Perhaps two signal falls off the effect is to move opposing diodes across the input would Ref. 3, Source of 0.5mm tinplate sheets fairly quickly to the 870MHz condition provide some protection against approx. 860mm by 800mm about £5.00 but it doesn’t jump there and if possible overload as available power each (as at June 98): Lancaster & measuring frequency by tuning a rapid levels increase. Winter Ltd, Steel Stockholders, increase in tuning rate can be noticed. Bradford, West Yorkshire, BD8 9AE, Please don’t think that you have Future developments using this Tel: 01274 498454. discovered a new way of generating prescaler will be a 10GHz PLL using 6.9GHz. possibly a Gunn or DRO as the 10GHz

Visit our Web site at www.batc.org.uk to view or download electronic versions of recent issues of CQ-TV

This article first appeared in ETI assist those who wish to understand its the current action, which can be used, magazine, Volume 26 No. 2, March operation, or for further development. for instance, to set black bars at the top 1997. and bottom of the screen to give a letter box wide screen effect. Another In this article, Robin Abbott Operation of the mixer possibility is to set a black horizontal presents the first half of the video The standard mixer offers 12 fade/wipe border at the extreme top edge of the mixer/fader to accompany last patterns. These are illustrated in figure screen to disable copy protection on commercial videos (for legal uses issues sync separator. 1. The black area on the figure shows the direction that the wipe will take. only). For example, fade pattern 4 wipes a This issue we will look at a project black area from the right based on the CQ-TV 180 video sync of the screen towards the separator article. This is a video mixer left; if there is an input on and fader. The specifications for this channel B then channel A project are as follows: will wipe to channel B from right to left. If there It offers 12 different slide wipe and is no input on channel B fade patterns, with considerable scope then the screen will wipe for other patterns to be generated by to black from right to left. further development of the control program. Selection of pattern and fade The mixer/wiper has four control by four-button keypad and dual pushbutton controls and a seven-segment display. rotary speed selection control. The four Automatic fade/wipe by push button pushbuttons are: pattern control. Control of fade/wipe speed up, pattern down, start from less than 1 second to around 20 fade, and start unfade. To seconds. select a pattern the pattern up and pattern All effects controllable by a PC on a down buttons select the standard serial port, allowing pattern number which is The decimal points on the displays are programmed fade/wipe effects. displayed on the two-digit display. also used, as shown in figure 2.

Uses a PIC microcontroller to reduce Once the required pattern is shown, The rotary speed control is used to costs. then the start fade button will put the select the fade speed. The actual speed screen to full brightness and then will of the fade depends on the chosen This project is interesting, not only in start the fade. Similarly, the start effect. For example, pattern 1 which is its own right, but also for the insight it unfade button will black the screen and a line by line fade will be twice as fast can offer into the use of real-time then return it to full brightness using as pattern 8, which fades two bars from computer-controlled systems, the selected fade/wipe pattern. each end of the screen at the same time. particularly those for video control. All The reason for this is that it achieves the software in the project is available During a fade or unfade the pattern up the maximum resolution of fading at in source code commented form to and down buttons may be used to stop any speed (resulting in the smoothest fades), and in practice is also easier to program. The use of a PC control for the display is shown later in this article.

Circuit and theory The circuit diagram of the project is shown in figure 3. The heart of the project is the PIC 16C74 microcontroller, described below. This device controls the analogue paths used in the project, handles the display multiplexing, and provides two analogue voltages used for control of fading and side to side sliding. The serial interface is also

Page 14 CQ-TV 185 © 1999 by the BATC handled through the 16C74. board is used to control the fading of controls over the video signal using the input channels, and the direct select SELECTB. These are called B input SELECTB logic signal is used SWDIRECT and SWINVERT. The sync separator board to switch between signals for the wipe SWINVERT simply turns on an The sync separator board shown in last effects. inverter on SELECTB. The month's article forms the switching and SWDIRECT signal is wire-OR'd with fading capability for this project. The The direct control of the video signal, the signals produced by the horizontal frame and line valid signals are used to accomplished through the SELECTB effects circuitry, to achieve this the indicate the position within the line and input on the sync separator board goes SWDIRECT signal is only ever driven frame of the video signals to control the low to select input A, or high to select low, or to a high impedance state, this switching. The VGAIN input to the input B. The PIC has two direct is achieved using the tri-state control

© 1999 by the BATC CQ-TV 185 Page 15 port on the PIC. would require a fast processor and the sync board. This is used to short would occupy a very significant out, and reset the integrator capacitor. amount of processor time in line The components which achieve this are Vertical wipes timing. For this reason the horizontal IC1a and IC2a. To obtain a symmetric The vertical effects require the video effects are generated by analogue based switching effect, the output of IC1a is signal to be switched on and off during techniques. In part 1, we looked at fed to an inverter and summer, IC1b the frame. For example to produce a horizontal wipe effects using a which produces an inverted triangle black bar along the top of the screen monostable. This would be possible in wave. The symmetry of the signal is (pattern 1) then the video signal must this project, but the monostable would controlled by variable resistor R6 - the be turned off at the start of the frame, have to be voltage controlled. In only preset control in the project. and then turned on at some point during addition to this, the effects with bars at the frame. For effects with a bar at the each edge of the screen require two To switch during the line period, two top and bottom of the screen, such as switches operating symmetrically comparators (one for each triangular pattern 8, then the video signal must be across the line. This is not easy to waveform) are employed. The turned off again further down the comparator used is the LM393, which frame. This effect is handled entirely within the PIC. To look in detail at a particular pattern, we will consider pattern 8 (the letterbox effect).

You may recall that the sync separator project shown in part 1 (CQ-TV 180) provides a line valid signal which goes low during the period of the line sync pulses and colour burst signal. This signal may be used as a line counter during the frame, and is connected to a 16-bit counter (TIMER 1) inside the PIC, the PIC may be set to produce an interrupt when this counter overflows. At the start of the frame, TIMER 1 is set to a negative value, and the video signal is turned off. During the frame TIMER 1 increments once on each incoming video line, eventually it overflows and causes an interrupt. The interrupt handling routine turns the video signal on, and loads another negative value into TIMER 1. When the timer overflows again, the video signal is turned off for the lower black bar. No further action is taken until the next frame.

To cause the bars to slide up and down, the values loaded into TIMER 1 during the frame are changed at the end of each frame. Slower slide effects are created by changing the value in TIMER 1 less often.

accomplish with monostables. is a dual device with a common Horizontal wipes collector output. A fixed reference The horizontal effects have to be An alternative method was chosen for voltage is used by the comparators, generated much more rapidly as video this project. A triangle wave is which switch the video signal when the triangular waveforms reach the same switching must occur during the 64µs generated, which is reset to 0V at the level as the fixed reference voltage. By available during a line. Although a start of the line, and which then rises software solution may be possible, it through the period of the line. This is changing the reference voltage, the achieved by using switching point may be controlled, and an integrator, which the wipe effect is generated across the is reset, at the start line. of each line by using an inverted The voltage used on the comparators is form of the line generated by the PIC, and uses one of valid signal from its pulse width modulation outputs. The

Page 16 CQ-TV 185 © 1999 by the BATC use of a PWM signal to generate a variable voltage is shown in figure 4. The PWM output is used in 8-bit mode to give 256 voltage levels across the screen, which provides a smooth wipe effect. The PWM output is smoothed by R25 and C6, which are chosen to filter the 20kHz PWM signal, but to allow the voltage to change in steps at frame intervals.

The outputs of the waveform comparators are wire OR'd with the SWDIRECT signal from the PIC. The outputs of the comparators are enabled when required using analogue switches IC2b and IC2c. These enabling signals are driven directly by the PIC on signals SWFALL and SWRISE. Figure 5 shows the waveforms in the horizontal switching circuit.

Direct frame fade To fade the entire video frame up or down the VGAIN input on the sync board is used. The second PWM channel on the PIC is used to provide this voltage. Note that it would have been possible to use the same PWM channel for the horizontal wipes but this wood preclude the use of combined horizontal wipes and frame fades simultaneously. The circuitry around IC5b is an active low pass filter, PIC 16C74 is assumed, however, which also scales the PWM voltage Serial interface understanding it is not necessary to which normally varies from 0 to 5V, The serial interface is a very simple and successful construction of the overall and converts it to a level suitable for cheap design. The input is tapped and project. the VGAIN input of the sync board - filtered to provide a negative supply for from -0.5V to +0.5V. the output voltage. The performance of The software consists of a main this circuit is adequate for any schedule loop, which calls subroutines application that does not involve large- to perform keypad, display, and Keypad and display scale duplex data transfer. fading/wiping processing. The actual The keypad and display are as simple switching of video signals is performed as possible to keep the cost as low as on interrupts. possible. A 2-digit 7-segment display is Other features used with a multiplexed drive. The The control of the speed of the fade or The heart of the control operation is the segments are driven directly from port wipe is through a variable resistor on use of the 8-bit and 16-bit D of the PIC which can drive up to one of the A to D converter inputs of timer/counters in the PIC. The 8 bit 20mA per bit (although there is a limit the PIC. This varies between 0V and timer is TIMER 0, and the l6 bit timer of l00mA per port). The digit drive is 5V with a resolution of 8 bits, although is TIMER 1. TIMER 0 is set to count taken via drive transistors Q2 and Q3. the software divides this by 16 to give on an internal clock which is the cycle 16 independent fade speeds. The fastest clock (in this design the cycle clock is The 4-button keypad is driven very speed is virtually instantaneous, the at 1MHz), divided by 128. Therefore simply on a 2 by 2 matrix. The PIC slowest is up to around 20 seconds for the timer increments once every 125µs, selects the columns one at a time, and the fade. and overflows every 33ms. TIMER 1 is reads the rows to determine which set to count on each line increment as button is pressed. As port B is used described in the section above on then the built in pull ups on this port Software operation vertical wipes. are enabled to avoid the need for It is instructive to consider the external pull up resistors. The keypad operation of the software for this The frame valid signal from the sync and display circuit diagram is shown in project, which is a mixture of real time board is used to cause an interrupt, and figure 6. control techniques and background this drives the edge triggered interrupt operations. In this section, some input on bit 0 of Port B. This interrupt familiarity with the architecture of the

© 1999 by the BATC CQ-TV 185 Page 17 is set to trigger on the rising edge of the either fully on, or fully off (Channel A three received bytes before they may be frame valid signal, and therefore all the selected or Channel B selected). This read by an interrupt service routine processing related to the frame is may be achieved in a number of ways. (ISR). The transmitting routine holds a undertaken at the top of each frame. To However to ensure that all fades/wipes byte currently in transmission together guarantee that processing is exactly start from the same condition the with a cache register which holds the synchronised to the frame, then the display is set into a known state at the next byte to be transmitted, this allows interrupt routine waits for the end of end of any fade/wipe or unfade/wipe. continuous transmission at the current line (using the line valid signal) before For example, “fully on” has VGAIN set baud rate without interruption for the performing further processing. This is to +5V, SLIDEVOLT set to 0V, ISR to write the next byte. important to ensure that TIMER 1 is SWRISE and SWFALL set to 0 written at the same point in each frame (disabling the outputs of the The 16C74 has three timers and a - if not then the vertical wipes will have comparators), SWINVERT set to 1 and capture compare register. The first an unpleasant juddering effect when SWDIRECT set to high impedance timer is an 8-bit timer, which causes an held stationary. (and therefore pulled high by the PORT interrupt on overflow. In this project B pull-ups on the PIC). Timer 1 the timer is used for display Interrupt processing is limited to interrupts are disabled. multiplexing and provides a writing the correct value to TIMER 1, replacement for the frame interrupt in switching the video signal on or off, When a fade or unfade starts, a routine the absence of a video signal. The and setting a flag to indicate that a new is called to set the display into an initial second 16-bit timer (TIMER 1) is used frame has been processed. After this state which is the same as the current to count lines within the frame, and processing returns to the main loop. state, but is ready to undergo the fade provides 16-bit resolution. The third The interrupt processor also deals with or wipe. For example, in the case of a timer is 8-bit, and has a preset register, the serial port using the built in serial horizontal fade the SWRISE/SWFALL which may used for providing any hardware of the PIC. The serial port switches must be set together with the output frequency in the timer range, interrupt is only enabled at the top of correct state on the SWINVERT signal which is used for the PWM outputs. the frame to avoid any chance of serial and the correct voltage on The capture/compare register is used interrupts breaking into video switching SLIDEVOLT for capturing the time of events. interrupts. Through the period of the wipe or fade In common with all the devices in the To enable processing to continue while the voltages on the PWM outputs, or 16C7X range the 16C74 contains an there is no video signal then the the values pre-loaded into TIMER 1, A/D converter. This is switched by an TIMER 0 interrupt is used. If TIMER 0 are changed at the start of the frame, 8-way multiplexer to up to 8-analogue overflows (when it counts from 255 to values are changed more rapidly with input ports, the reference voltage is 0), it causes an interrupt which is used faster slide speeds. selectable internally, or again from an to set the new frame flag, this will external source. The A/D converter occur every 33ms. However, if a video The fade or wipe routines are called contains an internal sample/hold circuit signal is present then the frame indirectly through a look up table, and has a maximum conversion interrupt will always occur within which enables straightforward addition frequency of 50kHz for 8-bit 20ms. This is used to reset TIMER 0, of further routines for additional resolution. and it will not overflow. Therefore a patterns. TIMER 0 interrupt will only ever occur The 16C74 runs the standard PIC in the absence of a video signal. This is assembly language, and can be used to set the decimal points on the The PIC 16C74 programmed serially both out of circuit display as shown in figure 2, and to The PIC 16C74 is the largest device of and in-circuit by most PIC disable the fader/wiper in the absence the 14 bit series of PIC controllers. It programmers. of an input signal. contains 4k of EPROM, and is housed in a 40-pin package, which allows three In the next article, which completes the The main loop handles the keypad and 8-bit ports and additional 5-bit and 3- fader/mixer, ~ will look in further detail display, and calls the routines to deal bit ports. The microcontroller has 192 at the setting of the various signals in with the progression of fading and bytes of ram available for use by the circuit to achieve each of the fade wiping. The display operates on a 4ms application programs. The and wipe patterns. We will also look at multiplexing cycle and is driven from microcontroller holds a large number of changes required to provide additional TIMER 0. The multiplexing routine is peripheral devices detailed below. patterns, and the detailed electronic and called every time that there is a change Despite the size and versatility of the mechanical construction of the project. to the top three bits of the timer. device it is reasonably cheap, and is a We will also look at providing PC very cost effective embedded control control of the mixer for programmed The keypad is read every time that solution. effects. there is a new frame by using the flag set by the interrupt routine. The keypad The device contains an asynchronous routines directly call the appropriate serial interface and baud rate generator. action subroutines if a key is pressed. The serial interface is interrupt driven. Unlike a software implementation the When a fade or wipe is not under way, asynchronous interface operates during the display may be in one of two states, program running, and caches up to

By Alan Kendal, G6WJJ display is easily modified to give a fact that the Morse routine is fixed call sign, as used by a number of repetitively accessed fifty times per A simple controller was required for the Beacons Repeater Group members. second. The processor is too busy to be the Sedgley 3cms repeater GB3BG, so The greyscale code was shortened to able to generate the audio tone so an being a big fan of PIC controllers I set free up some of the program memory external oscillator is keyed to generate about modifying the Picdream and an audio morse routine written that the morse. software. runs during one of the black lines of the Although the repeater timing routines could have run in place of other black lines, a lack of program memory dictated that a second PIC16C84 was used for repeater timing. This second processor could be programmed to generate the Morse audio but lack of development time has prevented this so far.

The control line to the audio oscillator is an open drain output and is high to The Picdream article featured in a original Picdream programme. enable the oscillator. The monochrome previous CQ-TV gives scrolling text on output, if used, needs to be terminated the top third of the screen, a greyscale Two look up tables were included to in 75 ohms to achieve correct levels. pattern across the middle and a digital store the coding for the call sign and The input signal present on the timer clock display at the bottom. The clock the ‘K’. The timing is derived from the PIC needs a high level to indicate signal present, opposite to that available from an NE565 phase lock chip.

The simple controller thus consists of only two PIC chips and an audio oscillator. To generate colour bars instead of a greyscale pattern only requires the addition of a colour encoder chip. The software listings are Simple TV Repeater Ident available on and Controller the BATC website or from me, telephone 01384 894512 weekdays 7- 9pm only please.

By Andy Emmerson G8PTH see little value in harping on about old one camera, then a second and an array television cameras in this magazine; of 8.5” picture monitors. The sound and Equipping a television studio is no big my only excuse is that these cameras vision mixers followed later and more deal if you have the budget; it’s just a are rather different from the usual recently I acquired the 14” station matter of placing orders and writing image orthicon types described and monitor. Most recently I have been cheques. The task takes on another more than just cameras are involved. very fortunate in finding the Master dimension when you decide that the Control panel and talkback console. studio you’re building is to use forty- My project is in fact re-creating the Pye year old equipment, all from the same Cambridge Studio, designed around None of these items was complete or in manufacturer and period. 1960—by BATC member Ian Waters working order, although most are now G3KKD as it happens—as a low-cost approaching that state. Some had to be re-sprayed in the proper colours, others needed new parts made. Only one camera control unit has turned up so a solid-state replica is being made. Even finding the right Dallmeyer fixed-focus lenses was a quest in itself but was finally sorted out earlier this year. Finding spare valves has never been a problem but if any more line output transformers die (the weakest point of Pye equipment) there will be problems!

It’s remarkable how self-sufficient the Pye group of companies was; within their ranks were Cathodeon (making camera tubes and crystals), Newmarket Transistors (semiconductors), Labgear (amplifiers), Magnetic Devices (relays) and Power Controls (multiway connectors). Many of these parts feature in the Cambridge Studio, whilst other items were left to the customer to buy in (such as studio lighting and microphones—Reslo ribbon types were commonly used). Classroom scene with the Cambridge Studio equipment in action

That, however, is the challenge I have ‘packaged’ television station for set myself over the past ten years or so; educational use and developing nations. it’s also the reason for the sometimes To contain costs to the minimum, cryptic small ads I have placed in CQ- vidicon cameras (called ‘staticon’ TV. Now, with the project coming cameras by Pye) were substituted for much closer to fruition, I thought an image orthicon jobs, whilst other explanation and description might be of facilities were fairly simple and basic. interest. There are some people who Back in 1962, £17,000 would buy you the complete station, with four cameras, two 16mm telecines, 100 watt transmitter, mast, aerial and everything else.

I can’t say I have spent that much on my own Cambridge Station, although the hours spent hunting down and Pye Mk4 camera restoring the equipment feels like it. Nearly all items have I think Pye would have claimed the been acquired at BATC Cambridge Studio was reasonably swap meets or though fellow successful; there were some showpiece Connector made for Pye by Power enthusiasts. It started with educational installations in Glasgow Controls Page 20 CQ-TV 185 © 1999 by the BATC and London, whilst a few systems were viewfinder failed, you could rob a said, they don’t turn up very often. I am shipped out to Commonwealth picture monitor from stores or from the also missing the ‘transcription unit’, countries as well. Subsequently a solid- control room! Pye’s rather grand name for a grams state educational camera was developed deck console, and the telecine around the Pye Lynx; this was called In appearance the cameras are equipment using a Philips EL5001/88 the Tele-Tutor. The heart of the camera essentially scaled-down versions of projector. Also needed are two female used in the Cambridge Station was an normal studio cameras, complete with four-way connectors (see photo) and all-valve Mk 4 industrial camera; this focus handle and four-lens turret (see larger plugs and sockets of the same normally had a barrel-shaped case but drawing). In fact ABC and Thames design. If you can help with any of this was concealed inside the ‘studio’ Television also used these models for these, I’d be very pleased to hear from style case that also housed a standard cameraman training at Teddington. I you. Finally, for those who may be 8.5” picture monitor used as a have two in the collection but I’d interested, I hope to bring part of this th viewfinder. This also illustrates the willingly augment this number; that equipment to the BATC’s 50 modularity of the concept; if a anniversary display this summer.

A tribute to Barry Keedy, G6LIC

Barry died suddenly in June 1998. He component for a comrade. Barry over filled the church at his was to many, a constant friend and passing. Condolences were passed to enthusiast for whom nothing was too The Yorkshire net knows that Barry his family from a large group of hams, much trouble. He combined his was pivotal in our most enjoyable too numerous to mention and technical communication skills with the nights on the air. His quick wit and bewildered by sudden loss. comfort of his personality. Even the spontaneous laughter are irreplaceable. most serious subject became Tony G1EFF describes our loss exactly It is not possible to think of Barry punctuated with the laughter that filled when he said “Our shacks are empty without a smile to meet memories of his life. We are all the poorer for his Pete!” the man who laughed so readily. We passing. almost heard him chuckle as the priest Not many people appreciate the extent misread his call sign from the pulpit. I met Barry on 70cms in the early 80's. of his work in developing and keeping Over the years we met infrequently but the GB3ET repeater. From the start he Barry Keedy G6LIC spoke little of his spent hundreds of hours working toiled to make this a possibility, in achievements but they do speak for simplex, duplex and 'multiplex' on construction, organisation and fund him. Not in material terms, but in his bands through to 3cms. For everyone, raising opening the door to many on humanity and personality. This is Barry was always the Pal ready to 24cms. He always spoke of results, not everlasting in the minds of all that answer the CQ or pop up P5 on any his own dedication applied to make knew him. band. He would range wide to test from things happen. a new mobile site or drop in some vital Peter G4RNA and ATV pals.

)UHH,QWHUQHW'LDO8S$FFRXQWVIRU%$7& PHPEHUV

Caladan Communications, a UK based Internet Services Provider are pleased to be able to offer BATC members free dial-up access to internet e-mail and news services. Contact Chris Smith (G1FEF) for more details:

E-mail: [email protected] Fax: 01933 666972, Web site: http://www.caladan.co.uk/batc

Or write to:

‘Free BATC offer’ Caladan Communications 25 Dando Close, Wollaston, Northants, NN29 7QB

By Rob Krijgsman, PE1CHY

To build a good FM-tuneable transmitter for 23 or 13cm is in theory not very difficult. A number of circuits have been published in amateur magazines. Practice, however, is a different story. Often, the most difficult part is the oscillator (VCO) which usually has a vague three-dimensional structure and needs a lot of patience and the right measurement facilities to be made to work. Another source of trouble is the PLL that is occasionally used (does not want to lock, spurious products, etc.).

Commercial VCOs The heart of this tuneable transmitter, the VCO, is an off-the-shelf module from Z-Communications. This Fig. 1. The completed transmitter shown fitted with a VCO/PLL for 23cm company supplies VCOs for a wide 250kHz. R3/C1 and C2 form the PLL variety of applications and frequency The circuit diagram bands. By choosing the right type of loop filter. VCO, a transmitter can be built for The VCO U1 works on a 12Volt supply 23cm (VCO 800 - 1600MHz), that can and the tuning voltage is between 0 and The video signal (including sound sub- also be used as a tuneable transmitter 20Volts. The output is an RF signal of carrier if present) is superimposed via for 3cm, by mixing, or for 13cm (VCO about +7dBm. The VCO output signal the pre-emphasis filter on the tuning 2000 - 2500MHz), that can be used as first passes through a T-attenuator voltage and in this way produces the well via multiplying to 3cm. comprising of R15 - 17. The desired FM-modulation. C22 attenuation has to be chosen in compensates for the attenuation of the accordance with the desired output higher frequencies due to the input capacity of the VCO. The frequency modulation characteristic for video is linear up to about 5MHz. The commercially produced VCO, free of phase noise is much better than the ‘floating’ BFR91 type of construction often used by amateurs. The ready made VCO-module is built in SMD technology and so the complete VCO/PLL unit can be kept very compact. Fig. 13 Photograph of the completed control unit power. With the MMIC IC1, the output Control unit Pre-emphasis power can subsequently be increased to Setting the division factor of the The transmitter uses a standard CCIR- 10 - 50 mW. Tuning is accomplished synthesiser, and hence the generated 405 video pre-emphasis, so that a video via a Philips I2C device, type TSA5055 frequency, is done via the I2C bus. The source can be connected directly. To (or SP5055). This IC includes a control unit (with the dial, LCD display transmit sound along with the signal, a complete PLL-synthesiser, including a and microcontroller PIC16C84) is baseband circuit is necessary with the prescaler up to 2.6GHz. With a located on a separate PCB that is sound oscillator(s). Check there is no directional coupler a very small part of connected to the transmitter section pre-emphasis in the baseband. If this is the output power of the signal (around - with only a few leads. With the not the case, and it is difficult to 10dBm) drives the sensitive prescaler included software, tuning in steps of disconnect, then the pre-emphasis in input of the synthesiser. The crystal X1 250kHz is possible. the transmitter can be removed by controls the reference signal. With the leaving C3, C4, R7 and L1 out of the crystal for 4 MHz used here, a circuit. minimum step size of 125kHz is Use of the control unit possible though, for practical reasons, The microcontroller software has the the control software cannot go below following features: Page 22 CQ-TV 185 © 1999 by the BATC Fig. 2 The circuit diagram for the VCO/PLL unit

Adjustment of frequency step (small The minimum frequency Now the text ‘Fr min: 1240’ (the and large) number may be different!) appears. The By pressing S2 while turning the dial, The maximum frequency minimum frequency can be adjusted the step size is increased to be able to with the dial in steps of 10MHz. The tune faster over the band. The step size (large and small) lowest value that can be chosen is 800MHz, the highest value is 2500 MHz. Obviously, the minimum Auto save function Pressing S2 while switching on the transmitter enters the set-up menu. The frequency can not be higher than the If the frequency is changed, the new maximum frequency that is set. When frequency is stored automatically. text ‘Set-up Menu Vx.x’ appears. Release the switch and press it again. the value is OK, press S2 again. The When the transmitter is switched on it chosen value is stored automatically. is set to the last used frequency.

TX-PTT button The transmitter can control a coax relay, a modulator stage and a power amplifier. By pressing the S1 (the PTT button) the coax relay, the modulator and the power stage are switched on in that order. A programmed small time delay disables the power amplifier until the coax relay has changed over. When the PTT button is pressed a second time, everything is switched off in the reverse order. To be able to use this function, the hardware has to be extended a bit (fig 12).

Set-up menu With the set-up menu, the following things can be set: Fig. 11 Photograph of the completed VCO/PLL unit

Now the text ‘Fr max: 1300’ (the value message ‘I2C Err: bus low’ appears. better to have no contact at all in that may be different!) appears. The case. Make the PCB and the enclosure maximum frequency can be set in the 2 the right size. Drill the holes for the RF I C communication test. same way as described above. Finally, output connectors (SMA) and the During the communication between the the step size can be set; first the small feedthrough capacitors. Use 10pF feed- microcontroller and the TSA5055 the 2 step size and after that the large step acknowledge pulse from the TSA5055 throughs on the I C bus. For the size. The step size is adjustable from 1 baseband input a phono connector can is tested. If something is wrong with - 40 (250kHz per step, so from 250kHz be used. Drill a hole for this connector the communication, this pulse will not to 10MHz). When S2 is now pressed as well. After this, drill the hole for the arrive and the error message ‘I2C err: for the last time, the normal program is MAR or ERA MMIC in the PCB on adr C0’ appears. (C0 is the hex entered. (MAR = 4mm, ERA = 2.5mm). Place address of the TSA5055) the SMD components, first the resistors and then the capacitors, then T1, the Software tests Construction PLL-IC and finally the VCO. IC2 and To make searching for possible errors the VCO are static sensitive! Now File a bit of copper away from the edge solder the PCB into the enclosure (only easier, a number of tests have been of the PCB, where the VCO has to fit the copper side) and fit the normal built in: (only on the soldering side). When the components. VCO is in place, it is not easy to move I2C bus short circuit test. the soldering iron around it to solder When the I2C bus, SDA line or SCL the groundplane to the enclosure. This The inductor L2 is used to supply DC line is shorted to ground, the error can result in a noisy contact, and it is to the RF output port for powering

© 1999 by the BATC CQ-TV 185 Page 25 transverters or LNBs used as up- capacitors. (on the soldering side). If necessary, the converters to 10GHz. When used as a 2.5mm holes have to be adjusted a bit. 13 or 23cm transmitter, L2 is not After that, the print with the display, necessary. Finally, attach the leads Control unit the rotary-encoder and the buttons can from the PCB to the feedthrough First, the display must be made to fit

Fig. 12 Circuit diagram of the optional PTT control

Page 26 CQ-TV 185 © 1999 by the BATC Fig. 7 Control unit circuit diagram be made to fit in the enclosure. components on the component side. This will later become the back. Use an Making it operational Make the holes for the front panel and 18-pin IC socket for the controller. The First, test the control unit without the drill the holes to attach the PCB on the rotary-encoder, buttons and the display microcontroller. The display should corners via spacers to the front. The are going to be on the soldering side. light up. Turn the trimpot completely to illustration of the soldering side can be The display can be attached with 5 mm the right. A number of dark squares used as a template. First, place the nylon bushes and M2.5 bolts. should be visible. Switch off the unit

© 1999 by the BATC CQ-TV 185 Page 27 and fit the microcontroller. The IC is boundaries, but this is not guaranteed. the produced harmonics further, to static sensitive! Reconnect the power Now measure the collector voltage of comply with licence regulations. supply. The display should show: ‘I2C T1. For the 13cm transmitter this err: on adr C0’ and a moment later the should be around 13 Volts at 2350MHz A complete kit of parts for the project frequency. Adjust the contrast, as you and for the 23cm transmitter around is available from AddCom MicroWave wish, to suit the brightness of the 9Volts. Now turn the dial. The voltage for 275 Guilders (about £85). background. The range of adjustment is should change with the frequency. If not very wide, most of the time the everything works OK, then the video Their address is: Hazendonk 18, NL trimpot is nearly on 0. Now connect the baseband signal can be applied. Adjust 5103, GH Dongen, The Netherlands. transmitter. Avoid static discharges the deviation control, P1 until the right Email to: [email protected] when soldering the I2C lines. When swing is obtained. The circuit needs no switched on, the error message ‘I2C err’ further tuning. should not appear, even momentarily. Specification of the 23/13cm The transmitter needs about 20V tuning tuneable ATV transmitter Output power voltage in the 13cm version. In the project 23cm version the tuning voltage can be The attenuater network R15 - 16 - 17, connected to the 12Volt line. can set the output power. For optimal Frequency range: 2320 – 2450MHz stability of the VCO the manufacturer (max 2000 – 2500MHz) recommends a pad of 6dB minimum. Resistor values for attenuater The output power of the VCO is about Tuning step : 250KHz minimum 7 dBm. A MAR11 still produces Attn. R15 = R17 R16 approximately 6dB gain for 13cm. O/P power : Pre-set up to 50mW max With a minimum attenuation (with R15 6dB 16 66 = R17 = 16ohm and R16 = 68ohm) this Harmonic level : -15dB or better 7dB 19 55 gives 7 – 6 + 6 = 7dBm or 5mW output 8dB 22 47 power. An ERA5 has a maximum out Supply: 12V DC at 200mA (including 9dB 24 40 power of 80mW (19dBm) with 18 dB control unit) and 20V at 2mA 10dB 26 35 gain. The VCO produces 7dBm. With a 11dB 28 30 minimum pad of, say 8 dB, we arrive at 12dB 29 26 Modulation : FM Deviation 20MHz 7 – 8 + 18 = 17dBm or 50mW. These max 13dB 32 24 values can be obtained by taking the 14dB 33 21 nearest standard values or by putting Mod bandwidth : 10Hz – 6MHz at 3dB 15dB 35 18 resistors in parallel. I advise 8dB pad points (22 and 47ohm). With a MAR11 you Now call the Set-up menu. Set the will have about 5dBm (about 4mW) or minimum and the maximum with an ERA5 about 17dBm (50mW). © 1998 by Repeater magazine. frequencies, keeping in mind the range of the VCO in use. For the V1200 type Information about ‘Repeater’ magazine the minimum frequency is 800MHz, Note can be found on their web site at the maximum is 1600MHz. For the The tuneable transmitter will normally http://www.euronet.nl/users/rulrich, V2250 the minimum is 2000 MHz and be used together with a power email: [email protected] the maximum is 2500MHz. Most of amplifier. This amplifier has to reject them go slightly outside these Deadline

Will all contributors please note that submitting an article for publication. the deadline for articles for CQ-TV 186 th is February 18 1999. Please send your The CQ-TV A4 size Word 97 contributions in as soon as you can document template can be downloaded prior to this date. from our web site. Select the CQ-TV magazine link from the home page at If you would like to contribute an http://www.batc.org .uk article for publication in CQ-TV, then please send it to the editor, either by All adverts, both members and post, or preferably by email. If you commercial, should be sent to Chris don’t use a word processor, plain Smith, the advertising manager, at 25 ASCII text is fine. Please see page 2 for Dando Close, Wollaston, Northants, address details. NN29 7QB.

Will all prospective contributors please Email: [email protected] by no later be sure to read the ‘Notice to than the 12th February 1999. Contributors’ on page 1 so that you understand the implications of

VHF COMMUNICATIONS magazine is published quarterly and is available from KM Publications, 5 Ware Orchard, Barby, Nr. Rugby, CV23 8UF, England.

Telephone: 44 (0) 1788 890365, Fax: 44 (0) 1788 891883 Email: [email protected]

The 1997 subscription rate is £18.00 for cash or personal cheque (drawn on a UK bank, or bearing the name of a UK banking agent), postal orders or bankers draft made payable to VHF Communications. Payment may also be made by any major credit card at £18.90. The subscription included surface mail charges, airmail is extra at £6.50 per year (£6.85 by credit card). The magazine is a MUST for the radio amateur and professional engineer interested in VHF, UHF and Microwave working, containing, as it does, detailed construction articles for equipment operating in these bands.

Back Issues: special offers - enquire for details Binders to hold 12 issues ...... £5.50 Complete Index 1970 - 1995...... £2.75

Email: [email protected] Web site: http://www.vhfcomm.co.uk Secure credit card page: https://www.vhfcomm.co.uk/saleform.htm Severnside Television Group

All of our 23cm Aerials are specifically designed for ATV use - although they can be used for other modes as well. Wideband characteristics mean that you need only one aerial to cover the repeater input and output channels. Our famous wideband yagis come fully assembled in two versions:

38 ELEMENT HIGH GAIN: 14 dB gain, 1.8 m long, £26.00 plus postage. 18 ELEMENT STANDARD: 10 dB gain, 0.9 m long, £15.00 plus postage

Don’t forget our 20 ELEMENT CONVERSION KIT, which converts your existing 18-element aerial to the full 38-element high gain specification: £13.00 plus postage. Our 23cm TROUGH REFLECTOR is quite unique, combining 11dB gain with wide bandwidth and wide beamwidth. It’s also compact, just 0.55 m high, 0.35 m wide and 0.3 m deep. Supplied as a kit of predrilled and preformed parts for easy “Screwdriver” assembly: £19.00 plus postage. All aerials feature an SWR of less than 1.5:1 and are supplied with mast clamps suitable for masts up to 55mm diameter. Mast poles shown are not supplied.

POSTAGE: £3.75 for one aerial, £5.00 for two or more. Telephone orders with cash on delivery: £2.75 supplement per order, Orders from outside of the UK - please write for carriage quotation.

CHEQUES payable to “SEVERNSIDE TELEVISION GROUP” and send to 18, Linnet Close, Patchway, Bristol BS12 5RN. Telephone (evenings and weekends only please) 0117 969 8136. Please allow 28 days for delivery.

By Paul Holland, G3TZO. Eutelsat II-F1 at 13 degrees East, II-F1 replaced I-F5 at 21.5 Deg E. Eutelsat I- F5 will co-locate with TV SAT 2 at Gazing into the crystal ball. 12.5 Deg W providing data services for A new year dawns yet again with the Moscow region. Eutelsat II-F3 is interest in Satellite Television being repositioned to 36 Deg E. continuing to shift from analogue to digital transmission and reception. In 1998 we saw little growth in analogue Nilesat services but an explosive growth in the Negotiations are underway with Matra number of digital feeds and DTH Marconi to build Nilesat 102, which services. will be co-located with Nilesat 101 at 7.0 Deg W. The satellite will carry, 12 The new year will see an acceleration transponders covering Africa, the of this trend with many familiar Middle East and South Europe. Using analogue services closing in favour of a digital compression the satellite will be digital alternative. This year should see able to offer up to 84 TV channels. the first of what could be called “2nd generation” digital receivers. At last we should see true multi-satellite capability Astra 2A Sirius 3 with seamless switching between A new digital free-to-air platform Here's the official transponder line-up analogue, DVB and ADR formats. started on Astra 2A, 28.0 Deg E on for SIRIUS 3: December 7. Called “Multiplex No. 1”, For the satellite DX ‘er we will see the it includes the new shopping channel • 11.785 GHz v continued trend in higher powered C Shop! (from Granada and Littlewoods), • 11.804 GHz h Band Satellites allowing reception in The Travel Channel, QVC, CNN the UK with more modest sub 2m International, Cartoon Network, and • 11.824 GHz v dishes. Look out also for lower cost TNT. The Welsh language TV channel • 11.842 GHz h services for high speed Internet access S4C Digital is likely to be the first • 11.862 GHz v via satellite as Internet Service broadcaster to use "Multiplex No. 2", Providers and satellite operators starting in early 1999. Eurosport is also • 11.881 GHz h compete for the continuing explosion in likely to join one of these FTA • 11.900 GHz v Internet traffic. multiplexes early in the year. • 11.919 GHz h • With transmission costs reducing it is Sky Digital plans to add at least 10 11.938 GHz v likely that we will see an increase in the channels in coming months.. • 11.958 GHz h number of both national and niche E!Entertainment, originally planned for • 11.977 GHz v broadcasters. The success of Eutelsat’s October, planned to start in January • Skyplex may see the introduction of with Studio Universal and "13th Street 11.996 GHz h independent “bouquets” comprised of a starting in February or March.. • 12.015 GHz v variety of special interest channels. Hallmark will follow by early spring, • 12.034 GHz h and BET on Jazz will make an • 12.053 GHz v Although Satellite TV reception is announcement about a launch date, also never going to satisfy the amateur thought to be in the spring. The launch purist philosophy of build and operate of 6 new themed channels from The As we closed for printing there were no your own equipment there is much fun Christian Channel has been pushed channel allocations announced. still to be had in assembling systems back from last October to February or and scouring the ether to see what is March. new in the world of Satellite TV. Happy New Year! Telecom France Telecom has decided not to Eutelsat News replace its four Telecom satellites Eutelsat has plans for 7 more orbital (Telecom 2A, 2B, 2C and 1C) when slots with new satellites at 12.5, 14.8, they end their service lives. The two and 19 Deg W aimed at audiences alternatives are to launch a new satellite through-out Europe, North Africa, and in 2005 or use Eutelsat. No final the Middle East. Further applications decision is likely before 2001. have been launched for 70.5, 76, 83.5, and 88.5 Deg E to reach Asia. Following Hot Bird 5 replacing

Page 30 CQ-TV 185 © 1999 by the BATC Launch News by; A. Around 25% of programmes will be in 16:9 widescreen now, increasing to Arabsat 3A Pressing “Services”, then Key,4,0,1 around 90% within five years. There Select. This will then reveal the will always be some archive material in Due to be launched on Ariane V116 Installation menu. 4:3 for many years after that. around now Arabsat 3A will be co- located at 26.0Deg E with Arabsat 2A. Q. Will regional versions such as BBC Arabsat 3A will carry 20 Ku Band Updating Software North West be available Transponders in the 11.7 – 12.1 GHz range. To force an update to software; A. No. • Unplug the receiver Date Satellite Position Launcher at the mains. Q. If the answer to the above is yes will I be able to receive all regional services • 9812 PAS6 43.0W Ariane Press and hold in the “Backup” button on A. See above the front of the 9901 Arabsat 3A 26.0E Ariane receiver while you Q. If I do not have a smart card from reconnect the mains. 9902 Eutelsat 36.0 E Proton B-Sky-B will I be able to get one from SESAT • Hold the “Backup” the BBC - if so when and where will button in until they be available. 9902 Astra 1H 19.2 E Proton “Download in progress” appears on A. To receive BBC Digital services, the screen. 9903 Eutelsat W3 7.0 E Atlas there is no need to subscribe to any Pay-TV services, but you may have to A normal update can pay more for an un-subsidised set-top take 8-10 minutes. Please 9903 Express A1 11.0W Proton box. The satellite box unsubsidised cost note that this only works around £360, I understand, compared to when you are connected 9904 Astra 2B 28.2 E Ariane £199 for a box subsidised by British via a scart to the TV Interactive Broadcasting (who also receiver. 9904 Eutelsat W4 36.0 E Ariane demand connection to a telephone line for 12 months). Any digital satellite 9906 Orion 2 12.0 W Atlas From the Post Bag retailer should be able to sell you one. Once you have the box you will need to Barry Gunstone writes 9907 PAS 1R 45.0W Ariane obtain a smartcard from the 'non-pay from Sweden to ask a TV customer access' number 0870 243 few pertinent questions 8000. 9908 TDRS 8 47.0W Atlas about the potential use of FTA Digital receivers for Q. If I have a smart card from B-Sky-B 9909 Hispasat 1C 30.0W Atlas reception of services will I need a separate smart card for from 28.2 Deg E. receiving BBC services or will the Sky Unfortunately I had to be card include access to BBC and other the bearer of bad news in Free To Air services. Digibox Corner that it will be impossible for the foreseeable future to use anything but For those owning or contemplating A. No. The non-pay services should be buying an official Sky Digibox there an authorised Sky receiver (Digibox). The reasons for this are that the automatically enabled along with your are a few things you will not find in the chosen Pay-TV channels, handbook. Internet News Groups are Mediaguard CAM used in the Digibox already buzzing with information on is not supplied separately. Even to Roderick Duncan, BBC Reception how to do the things Sky never receive so called FTA services such as Advice. intended you should. So with the usual Sky News it is necessary to have a disclaimer for liability I am valid smart card. These are available reproducing a couple of potentially either by subscribing to Sky or by Internet: http://www.bbc.co.uk/enginfo/ useful tips. ringing the BBC to obtain a card to receive BBC services for your area. If you live in England you will not be Channel News Launch Plan for 1999. able to receive BBC Wales or BBC Venezuela's Puma TV is now on Hot As usual these dates will change for a Scotland. Bird 2, 12.092 GHz.(H) SR 27500 – variety of reasons – not the least being FEC 3/4 Also here can be found the success or failure of preceding A reply provided by the BBC to some Cadena Sur, Sólo Tango, and a promo launches. questions I asked about BBC Digital channel for Vacaciones TV. All are Services is reproduced below; FTA.

Installers Menu. Q. Will all BBC services be widescreen CNBC Europe ceased broadcasting on Normally hidden this can be accessed (16:9) or standard (4:3) format. 11.265 GHz at 13 degrees East at the

© 1999 by the BATC CQ-TV 185 Page 31 end of November. It will continue in Module. various LNB’s. For those still unsure PAL on Astra transponder 50. here is a quick glossary of common Main features are; terms; Ski Channel- The International Ski • Federation says it will start its own Ski Symbol rates - 1-42 Ms/s Normal LNB - Fixed voltage single Channel within two or three years. It • SCPC & MCPC band LNB requiring a separate will carry programming that other polariser. • channels are reluctant to carry. RAM 2.0 Mbytes • SDRAM 4.0 Mbytes Voltage Switching – Single band with Deutsche Telekom will launch its own 13/18V switching of H/V polarity digital package consisting of Kanal D, • 1 x F Connector a-tv2, RTP International, TVP, ERT • DiSeqC 1.0 Standard LNB – Same as voltage Sat, and Zee TV. on Hot Bird 5. They switching but infers the use of a will be joined by RAI Uno, RAI Due, • Satscan 10.0Ghz local oscillator. RTS, HRT Sat, RTV, NTV, Antenna, • 2 x Scart and CNE. The package will be encoded Enhanced LNB – Can be either Voltage in Irdeto from 1999 July 1 Praxis Digimaster 9800 AD+P Switching or Normal and uses a local Although the Nokia 9800 is oscillator of 9.75 Ghz (Astra 1D use). RTL’s digital package launched in undoubtedly a big improvement on its November on Hot Bird 5 on 11.054 predecessors the Praxis 9800 would Universal LNB – Uses 13/18V GHz. It includes RTL, RTL2, Super appear to be entering a league of its switching for polarity and a 22Khz tone RTL, and Vox. own. This receiver can handle up to for switching between higher (11.7- 700 analogue channels and 2900 digital 12.75 Ghz) & lower (10.7-11.7) Ring TV has started on Hot Bird 1 at channels (1500 TV / 1400 Radio). frequency bands. 13.0 Deg E on 11.280 GHz in clear Reviewed in the January issue of Tele- PAL, 13:00-18:00 hrs CET. Satellite Magazine this receiver has Triple Band – Usually cover FSS, DBS true multisatellite capability with and Telecom frequencies using 13/18V Euronews has confirmed that it will motorised control and polarity skew. switching to select high or low bands. close down its analogue transponder on The key features are as follows; Requires a separate polariser. Hot Bird 5 11.585 GHz) on March 31.. • 3 Scarts The ITN-owned broadcaster began Quad Band – As for triple but includes digital transmissions on Hot Bird 3 in • 3 LNB inputs (+1 for loop Astra 1D frequencies and requires a January. through) receiver with a 2Ghz tuner. • SVHS Sima-yeh Moghavemat has moved Twin LNB – LNB with two separate from Eutelsat II-F1 to II-F2 at 10 Deg • Positioner (36v) 50 satellite outputs capable of switching E on 11.163 GHz, in clear PAL. positions independently between H&V polarities. • Sensor (Hall or Reed) Pakistan's Prime TV has launched a 6 Dual LNB – Has separate ouputs for H hour a day European service, soon to be • Mechanical (pulse) or 13/18V & V polarities and is used with IF expanded to 24 hours, on Intelsat 707 at polarity control switching devices usually TV in 1 Deg W in MPEG-2 (SR 26000, FEC distribution systems. 3/4) on 11.014 GHz. It is currently • DiSeqC clear, but will switch to Conax • 22kHz and 12v switching encryption soon. Conclusion • 2-45 Ms/s symbol rate selection That’s it again for this edition of Brazil's TV Record is on Intelsat 605 • RAM 2Mbyte / DRAM 2 Mbytes Satellite TV News. As usual the e-mail (27.5 degrees West) in clear MPEG-2 address is [email protected] (SR 7000, FEC 3/4) on 4.055 GHz.. • 18/27 MHz bandwidth or QTHR for any news and views you • Decoder socket (i.e. D2Mac) may have on the Satellite TV scene. New Products • 2 CI slots Nokia 9800 Around now you should be seeing the It seems likely that when the weather first Nokia 9800 receivers appearing in warms up enough to support a foray out Micro transmitters dealers shops. The Mediamaster 9800 to the dishes that this receiver could while away many a happy summer is the next generation of Nokia receiver A German company is offering afternoon. with much improved software for miniature television transmitters for use organising digital services across a on frequencies from 900MHz to number of satellites. The 9800 is Which LNB is which ? 2.4GHz, aimed at surveillance, amateur equipped with Satscan for multisatellite and radio-control aircraft users. The reception and has both a CI slot and an I no that many people are still confused website, in English and German, can be embedded Viaccess Conditional Access by the terminology used to describe found at www.videobug007.com

By Garry Smith this created a serious interference into thinking that the interference potential particularly where transmitter problem will be minimal and pose little Another notch in TV history was made footprints overlapped. threat to DX reception on the same on Sunday November 15th when the channel. World’s first digital terrestrial TV Initially most main transmitters to be service was launched in the United used by the new service were assigned In practice, the digital multiplexes have Kingdom. The service allows viewers Channel 37 (Croydon, Lichfield, Emley as much destructive power as the equipped with a set-top box to receive Moor, etc.) while later on Channel 35 higher level analogue signals. Some several free-to-air channels plus was used by ‘fill-in’ transmitters viewers served by relays are now subscription channels delivered by (Waltham, The Wrekin, Ridge Hill, finding their analogue pictures have ONDigital that is a consortium spear- etc.). Note that Channel 5 sites were deteriorated due to digital interference headed by Canton and Granada. not owned by the BBC, hence there are from distant main transmitters sharing high-power transmissions from sites the same frequency. Tim Bucknall Unfortunately, launching such a service such as Black Mountain which is used (Congleton) mentions this is affecting has not been without hiccups because only as a low-power relay for BBC and some viewers tuned to the Congleton terrestrial reception is unpredictable in IBA broadcasts. relay who are suffering digital many areas, unlike signals delivered by interference from the main Sutton satellite where, unless the dish cannot As a result, frequency sharing means Coldfield transmitter. see the satellite, the reception is that many viewers are in reach of two guaranteed. or more Channel 5 outlets but are In mild cases the interference effect unable to view interference-free shows as fine patterning over the pictures! picture, resembling that of a mis- aligned decoder or IF strip. In extreme cases a good colour picture as been Digital reduced to heavy snow with lack of Interference chroma. It is difficult to perceive a The introduction of digital signal on a normally blank digital terrestrial channel; the snow effect appears television has brighter or more intense depending increased the upon the type of TV receiver used. interference potential dramatically because Advantages of Digital each main transmitter has been Although digital transmission is more assigned six cost-effective and efficient in terms of additional analogue bandwidth used, it is unlikely to have channels each got off the ground unless there was Fig. 1: ONdigital logo used during field trials. The containing the digital money to be made from it. Basically it is packaged TV - the more channels background constantly changes colour. multiplexes. Examining the there are, the higher the revenue for the digital channel programme providers. Channel Allocations allocations reveals many instances In the Sixties, a UI-IF channel plan was where channels are shared by digital Many viewers were under the false drafted for the United Kingdom and analogue signals allowing a maximum of 4 channels per from neighbouring transmitter. This was carefully transmitters. For engineered to avoid interference instance, the channel problems resulting from transmitters allocations of Emley sharing the same channels. Moor and Sutton Coldfield provide Shared frequencies were assigned to mutual interference transmitters located geographically as potential in areas just far apart as possible in order to to the north of Derby minimise the risk of co-channel where their footprints interference under tropospheric overlap. Although the conditions. E.R.P. (effective radiated power) of the When Channel 5 hit the airwaves, digital signal is some unoccupied channel 37 (and later, 20dB down on its channel 35) was used to support a analogue counterpart, Fig. 2: Logo used by Carlton Cinema via digital ‘national’ TV network. Unfortunately, it is easy to be misled terrestrial television (DTT).

© 1999 by the BATC CQ-TV 185 Page 33 impression that digital TV would parameters via an on-screen menu! Boost the digital signal and you will provide ‘high-definition’ pictures. Not Later pre-production units became boost the analogue too. When adjacent so, although it could have been used for available and with these the channels analogue signals exceed 80dB[V the that purpose at the expense of could be changed by using the remote digital receiver may go into overdrive bandwidth and hence a reduction in the control. There were disnlay models by thus affecting the weaker digital number of channels. The over-critical various manufacturers but as one thief signals! TV fanatic (i.e. the ones who measure soon found out, ‘his’ unit was only a the squares on the test card with a ruler casing without innards! for correct geometry) may find fault with the digital picture if they are used to an exceptionally crisp Fault Diagnosis and clean analogue display. With analogue we know that MPEG-2 encoding means that if the signal is too high, digital bits of information cross-modulation occurs and required for fast moving scenes this will show as lines across are ‘borrowed’ from slow- the picture or ITV floating moving p arts of the picture mixed in with the BBC which means that the background signal. A weak signal will of say a football match may look result in a snowy picture. A unreal to the discerning eye. ghost image on the picture tells us that multi-path However, the overall picture reception is present. quality is consistent as correction is provided which eliminates Unfortunately, if ghosting normally created by intermittent break-up of the multi-path reception. In other Fig. 3: Alternative logo radiated by Carlton Cinema. digital picture occurs no real words, if your existing analogue clues can be obtained by picture from a main transmitter examining the picture. It (relays are not distributing the signal Plug and Play will be necessary to ensure that signal since there are no spare frequencies) strength readings are within tolerance has severe ghosting then a switch to The set-up menu is the same for all on both digital and analogue channels. digital could be the cure. The digital makes of receiver, so if you can work Generally speaking, a minimum level one unit you can work any. Simplicity picture is either there or it isn’t which of 32dB[V is required for the digital means that a fluctuating signal-level is the key word because of the ‘Plug receiver to work but a minimum level may result in the picture breaking up and Play’ concept in which the [ into squares and then freezing until the customer takes home the box, connects of 38dB V is recommended to take digital signal resumes a certain it to the aerial and TV and hey presto! into account signal variations. threshold With analogue the picture Success within minutes, or at least would have gone snowy. that’s the idea. A help-line is available Future aerial installations for digital which will assist viewers in carrying reception will be extremely hit-and- out basic checks in the case of not miss without the aid of a digital signal- Digital Tests having any success. strength meter. My own experience Some digital transmitters went on test suggests that this will be an invaluable during the summer, if only to assess the Dealers have access to postcode tool for the DX-er, otherwise we might interference potential to analogue mapping which allows them to tell the be misled into thinking that the blank broadcasts using the same channel. customer whether coverage is channel we see is void of signals when Only carriers were transmitted since applicable to their address. Of course, in reality there is a thumping big digital digital receivers were not available at someone will live in a sheltered dip signal present! the time to decode the signal. Pre- along a street where the signal is production units were launched for test insufficient yet at each end of the road purposes and these were used to the signal will be fine. Future Plans provide off-air pictures at the Earls Within the next two years, ONDigital Court Exhibition Centre towards the hopes to accommodate six further end of September. However there were Excessive Levels channels within its existing three digital problems with the off-air reception Although the digital signal has to be a multiplexes once unproved digital during the event which resulted in certain level otherwise dropout occurs, compression techniques become picture break-up. As a result, some of too much amplification can stop the available. At the moment, five channels the gutter-press reporters had a field decoder from working if the adjacent are contained within each multiplex at day condemning the new technology analogue ones become too high in an average data rate of 4-4.5Mb/sec. outright! signal strength as a result. Using high- Finally, the Crystal Palace signal is 3- gain antennas with lots of amplification 4dB higher than it was originally. Using pre-production models meant will be asking for trouble because the that the only way the channel could be digital multiplexes are some 20dB All photo’s supplied by Keith Hamer changed was by updating its technical down on the adjacent analogue signals. and HS Publications (Derby).

Publication Each Qty Total An Introduction To Amateur Television (225gm) ...... £5.00 ...... The latest handbook full of detailed information on how to set up your ATV station, plus lots of new video and RF construction projects.

Slow Scan Television Explained (275gm) ...... £5.00 ...... The latest SSTV handbook detailing all the information you need to enter the fascinating world of Slow Scan Television: Basic principles, explanations of all the modes to date, commercial hardware and computer-based SSTV systems. Also various construction projects for SSTV equipment.

The Amateur TV Compendium (155gm)...... £3.50 ...... The BATC handbook featuring construction articles on video units, 24cm and 3cm ATV, a Digital Frame Store, and much more.

The Best of CQ-TV (150gm) ...... £3.50 ...... A compilation of the best construction articles from CQ-TV’s 133 to 146

CQ-TV Back Issues: ...... £1.50 ...... The following issues are still available. Please circle those required: 142, 143, 144, 147, 150, 153, 154, 156, 158 159, 162, 163, 164, 166, 167, 168, 169, 170, 171, 173, 174, 175,176, 177,178, 179, 180, 181.

Special Offer: Any four of the above issues ...... £5.00 ...... 182, 183, 184, 185 ...... £2.50 ...... Index on a PC format disk (25gm) This item has now been discontinued, as this index is included on the BATC CD.

CQ-TV Binders (A5 sized) ...... £3.50 ......

The BATC CD (IBM type PCs only) ...... £5.00 ......

Total Goods and Postage - Amount Enclosed. £..……......

The indicated prices for Publications include postage within the EEC. Will members outside the EEC please either try to estimate the extra postage required, or write for a quotation. Publications orders ONLY to: BATC Publications, Fern House, Church Road, Harby, Notts., NG23 7ED, England. Tel: 0152 270 3348 (Evenings/Weekends only please). E-mail: [email protected].

Name: Mem No:

Address:

A description of the various PCB’s and components can be found in the ‘What’s What’ guide, or on the BATC Internet pages. URL http://www.batc.org.uk (A printed copy available on request, if you send a S.A.E.). Components for club projects are not available from Members Services unless contained within these lists. All club crystals are HC18/U (wire ended). To avoid delay and inconvenience, please be careful to include the correct payment with your order – please do NOT send stamps or cash. Post and packing costs are for despatch of one item to United Kingdom members.

Circuit Details can be found as follows: Revised ATV Handbook (vol. 2): PCB’s 21, 22. An Introduction to ATV: PCB’s 10, 25, 36, 40, 41, 47, 85, 86. TV for Amateurs: PCB 19. Slow Scan TV Explained: PCB’s 59, 60, 61, 62. Amateur TV Compendium: PCB’s 12, 27, 54, 55, 56, 57. CQ-TV (Issue No. in brackets): PCB’s 7(174), 13(128), 16(134), 20(130), 26(142), 58(139). Item 46 is supplied with circuit details, etc

CAMERA TUBES A tube guide appears in CQ-TV 149 and 150. Tubes are now difficult to obtain and members requesting information on availability, prices or other types of tubes or equivalents are asked to send a stamped addressed envelope for their reply.

All prices in UK pounds (£) Each P&P Qty Total

Camera Tubes, Scan Coils, Bases & Lens Mounts 3 One inch Vidicon base...... £1.20 ...... £0.30 ...... 4 2/3 inch Vidicon base ...... £0.80 ...... £0.30 ...... 6 Camera tube (see note above)...... * ...... £1.20 ...... Video and I2C Circuit Boards/Components 7 Sync pulse generator PCB ...... £12.00 ...... £0.43 ...... 12 Teletext pattern PCB**...... £3.50 ...... £0.43 ...... 13 Greyscale/Colour bar generator PCB...... £3.50 ...... £0.43 ...... 16 PAL colour Coder PCB** ...... £7.00 ...... £0.43 ...... 19 Video filter PCB ...... £1.20 ...... £0.30 ...... 20 Video processing amplifier**...... £4.70 ...... £0.43 ...... 21 Vision switcher matrix**...... £4.70 ...... £0.43 ...... 25 4 input TEA5114 vision select PCB** ...... £3.50 ...... £0.43 ...... 26 Video level indicator PCB ...... £5.90 ...... £0.43 ...... 40 I2C CPU PCB...... £10.00 ...... £0.43 ...... 41 I2C VDU PCB...... £10.00 ...... £0.43 ...... 42 13.875 MHz crystal...... £4.70 ...... £0.30 ...... 70 6.0 MHz Teletext crystal ...... £1.75 ...... £0.30 ...... 43 SAA5231 genlock IC...... £8.80 ...... £0.30 ...... 44 SAA5243PE Teletext IC...... £14.70 ...... £0.30 ...... 45 PCF8583 Clock IC...... £7.00 ...... £0.30 ...... 39 LM1881N Sync separator IC...... £3.50 ...... £0.30 ...... 81 I2C 27256 EPROM ...... £9.70 ...... £0.30 ...... 36 I2C Video switch PCB ...... £8.80 ...... £0.43 ...... 37 GX414 Video switch IC ...... £8.80 ...... £0.30 ...... 38 PCF8574P Input expander IC...... £4.70 ...... £0.30 ...... 10 I2C Relay PCB ...... £6.50 ...... £0.43 ...... 9 PCF8574A Input expander IC ...... £4.70 ...... £0.43 ......

Page 36 CQ-TV 185 © 1999 by the BATC All prices in UK pounds (£) Each P&P Qty Total RX, TX and SSTV PCB’s and General Components 47 ...... 70cm up converter PCB...... £13.50 ...... £0.43 ...... 50 ...... 108.875 MHz crystal...... £8.20 ...... £0.30 ...... 86 ...... 24cm solid state amplifier PCB ...... £10.50 ...... £0.43 ...... 55 ...... Gunn diode modulator PCB...... £3.00 ...... £0.43 ...... 56 ...... 10Ghz head unit PCB set**...... £3.00 ...... £0.43 ...... 57 ...... Tuneable IF PCB** ...... £3.00 ...... £0.43 ...... 58 ...... 6MHz audio subcarrier generator PCB**...... £3.00 ...... £0.43 ...... 88 ...... XR215 phase locked loop IC...... £5.00 ...... £0.30 ...... 60 ...... G4ENA colour etc. SSTV mod PCB set...... £5.90 ...... £0.43 ...... 61 ...... G4ENA SSTV transmit mod PCB...... £7.00 ...... £0.43 ...... 62 ...... G4ENA auxiliary PCB...... £2.35 ...... £0.30 ...... 68 ...... 4.433618MHz crystal...... £3.25 ...... £0.30 ...... 69 ...... 5.0MHz crystal ...... £3.25 ...... £0.30 ...... 46 ...... 4 Rail power supply PCB...... £3.50 ...... £0.43 ...... Stationery & Station Accessories 73 ...... BATC blue diamond clutchpin badge...... £1.75 ...... £0.30 ...... 74 ...... BATC cloth badge ...... £4.00 ...... £0.30 ...... 75 ...... BATC equipment label (6) ...... £0.25 ...... £0.30 ...... 76 ...... BATC square windscreen sticker...... £0.10 ...... £0.30 ...... 78 ...... BATC test card ...... £0.50 ...... £0.43 ...... 79 ...... BATC reporting chart ...... £0.10 ...... £0.43 ......

Total Goods and Postage - Amount Enclosed £..……......

Members Services orders ONLY to: Mr. P. Delaney, 6 East View Close, Wargrave, Berkshire, RG10 8BJ, England. Tel: 0118 940 3121 (Evenings, Weekends only please).

Name: Mem No:

Address:

Items from these lists can ONLY be supplied to CURRENT members of the BATC. These lists supersede all previous ones.

The indicated P&P prices are for postage within the EEC. Will members outside the EEC please either try to estimate the extra postage required, or write for a quotation. All cheques MUST be drawn on a UK bank. (Eurocheques, in £ sterling, are acceptable). Items marked thus: ** are available only until present stocks are exhausted. PLEASE MAKE CHEQUES PAYABLE TO ‘BATC’.

9GHz DRO pucks £6 each

Also small quantities of

8.6, 9.4, 9.75/9.8, 10.3 and 10.6GHz.

Exact frequency depends on operating conditions.

Cash or cheque made payable to:

Beacons Repeater Group,

40 Monument Avenue, Wollescote, Stourbridge

DY9 8XS, or telephone Alan Kendal G6WJJ

01384 894512 7-9pm weekdays

Dicky Howett enters his personal TARDIS, returns to 1958, visits the BBC Television Theatre and meets a few buskers

I was a telly-mad kid in the 1950s (not a lot has changed!) Back then, I applied regularly for free audience tickets to BBC TV variety productions. (ITV shows had a lower audience age limit of 16 years-I was then too young to enter commercial portals-so BBC shows it had to be). They included ‘The Ted Ray Show’ and ‘The Billy Cotton Band Show’. These creaky concoctions were produced live and dripping from an old converted West London theatre named the Shepherd’s Bush Empire, on Shepherd’s Bush Green.

A visit to the Empire (re-named in TV Theatre 1960s 1953, the BBC Television Theatre) was outing; a learning curve. always an adventure - a trip to the Big Buskers Galore Bad City and a chance to see real TV Another feature of the Television cameras in action! For an Outside the Television Theatre, during Theatre queue was the professional impressionable nipper, it was an the 40 minutes or so queuing time, the beggars. In those days there were two exciting time, full of mystery and programmes ‘stars’ would sometimes of them. The-Busker-With-The- wonder. wander out for a breather, or perhaps to size up the audience? (More probably Trumpet and The-Blind-Man-With- they were hoping to elicit admiring The-Matches. The-Blind-Man-With- On arrival at the Television Theatre I stares). Ever on the lookout for The-Matches did absolutely nothing, would join the queue, clutching my excitement, I once took my Box but instead, shuffled along the queue dedicated BBC ticket. I always liked to Brownie camera and photographed (with the help of his wife) muttering arrive early, because it was first come- comedian Terry Scott and singer Alan “Blind, blind”, and offering from his first served in the allocation of seats. I Breeze (of the Billy Cotton Band tray, matches in exchange for hoped for a front-row pew from Show). Also, I snapped a surprised donations. Not very entertaining. Then whence I could ogle all the technical BBC technician who got his picture came The-Busker-With-The-Trumpet. telly action. In those far-off days I taken just because he happened to look He would suddenly blast out, more-or- nursed youthful dreams of becoming a famous. less in key, several excruciating and TV cameraman so these trips to TV totally unrecognisable tunes. When studios, I considered as an educational he’d finished his act, he also proceeded along the queue in search of funds. The routine was always the same. Blind man first, then the totally Tone Deaf. It was a great relief to get inside the theatre.

At the time of my visits, (approx 1958/1960) The BBC Television Theatre was equipped with four Marconi Mk III 4 ½ inch image orthicon cameras. These large TV cameras produced dynamic pictures with comparatively little light. I had anticipated vast searchlights dazzling everything in the studio. In fact the illumination was quite restrained and logically directed using Mole Solar Spots and scoops.

Marconi Mk III cameras during ‘Crackerjack!’ Camera ‘One’ rode on a Mole Richardson counter-balanced crane

© 1999 by the BATC CQ-TV 185 Page 39 down the central stage ‘runway’. and flashy ITV. However, most was the power of television in those Cameras ‘Two’ and ‘Three’ were noticeable and most startling to anyone days, performers were regarded mounted respectively on a Vinten HP new to the sight of a television studio reverentially, as some sort of super- 419 pedestal (tiller steered only) and a was the sheer colour of it all; also the beings from outer space, and not like Vinten Pathfinder dolly, both on or clear, vibrant quality of the live audio. real people at all. Things haven’t around the stage. Camera ‘Four’ was Unfortunately, in 1959 both those changed much. mounted at the front of the dress circle. technical factors were missing from the This camera displayed a prodigious average cheapo 405-line domestic telly. Taylor-Hobson Mk I zoom lens. Of Curse of Wogan course, at the time I had no idea of In fact, strange to relate, those old-time The BBC vacated the TV Theatre in exactly what all the equipment was. All monochrome TV stars were not 1993 and as a parting gift they gave us of it looked to me, innocent sprog that I instantly recognisable in the flesh, so Terry Wogan who, as we all know, was, like arcane gadgets in a science used as we were to viewing them in finally killed the early evening chat fiction movie. Also, in my childish ‘glorious’ black and white. My mum show, (until the next time that is). ignorance I assumed that all tv (who accompanied me to several Fortunately, the old Theatre avoided cameraman needed to be super-strong shows) was utterly convinced that a the fate of some other BBC premises because the cameras--as I saw--were handsome BBC stagehand was Russ (ie: converted into ghastly theme enormous and intractable. These days I Conway. Whereas all the while, the studios, or worse, total demolition). know it was all too true! real Russ Conway, (known for his The Theatre has now reverted back twinkling smile and full front set) was (under new ownership) to its original incarnation as a ‘live’ venue for performances of all kinds, including trumpet involuntary and busking for matches.

New Cable Preparation Tools for Reliable On-Site Cable Preparation New automated tools give consistent cable preparation in just 10 seconds.

16th October 1998 - Andrew introduces EASIAX? PLUS automated cable preparation tools for 7/8-, 1-1/4- and 1- 5/8-inch HELIAX coaxial cable. These new tools attach to an electric drill and quickly cut the cable jacket, outer conductor and foam core to give consistent and reliable on-site cable connections in 10 seconds or less.

EASIAX PLUS automated cable preparation tools create fast, efficient cable connections for Andrew Corporation's family of standard and RingFlare? connectors. The tools are made from aluminium for ease of handling, reduced weight and resistance to corrosion. Each tool has three cutting blades that provide approximately 300 cuts before they need to be changed. Replacement blade kits are available and cutting blades are easily replaced using the socket wrench Terry Scott strolling past the queue. included.

Those early TV shows, however, sitting dumpy, hunched and For further information contact Andrew appeared far better in the flesh than unglamorous at the side of the stage and request bulletin number 10267 or they appeared on the home screen. At awaiting his cue. When Russ come on visit the website at the time, BBC light entertainment (as to play a tune, my Mum actually http://www.andrew.com. opposed to BBC heavy entertainment) thought he was an impostor, because he ran a very poor second - with less than didn’t ‘look’ anything like his 30% of the audience - to the glamorous appearance on the home screen! Such Page 40 CQ-TV 185 © 1999 by the BATC Worthing & District Video Repeater Group

GB3VR GB3RV & GB7VRB

1Watt FM-TV 24cms Transmitter

The 1 watt transmitter generates its signal at the wanted frequency which can be set anywhere in the band, colour or B/W. On board intercarrier sound and fixed pre-emphasis are standard features. The kit includes the PCB all the on board components, pre-drilled heat sink, an Eddystone Di-cast box and full and comprehensive instructions. Building time is three evenings work. The new price for this kit is £80.00, P&P £2.50. Over 750 units sold to the Amateur market alone.

Two channel phased locked loop kit.

This add-on kit vastly improves the overall stability of the 1 watt transmitter. Two crystal locked channels and a third free running tuning position are available. Kit price £30.00

Amiga ATV Program-2

The New Amiga ATV program has more features than ever, up to 56 testcards, 20 wipes, superb text control, 30 screens of text messages, QRA calc, Testcard music, selectable displays, and this version has a DTMF tone pad to control your repeater. All testcards are over-scan i.e. the whole screen is used, Load in your own customised testcards, Extra large text, scrolling text, clock, callsign extensions, Hot key operation, Doc reader, ATV Cli, Cross Hatches, Purity and a comprehensive section for genlock users. For any Amiga with 1meg or more, state callsign and QRA (if known) when ordering, this three disk set is now only £10.00 P&P 75p

Spectrum ATV Program

Still selling after all these years, why, its good, its cheap and it works on all spectrum based machines. The 48k version has over 60 commands which include 7 Testcards, Memo pad, clock, maps, tones, QRA locator, various size printing, plus disk transfer routines and much more. Now only £5.00 P&P 75p

Visit the all new GB3VR-RV web site at: - http://www.g8koe.demon.co.uk/

Orders should be sent to:-

Treasurer of GB3VR, R. Stephens, 21 St. James Ave., Lancing, Sussex, BN15 0NN. Cheques payable to "W&DVRG" Tel (01903) 765760, 7 to 8pm.

By Graham Baker, ZL1TOF ATV or Amateur TV - check out TV Each manufacturer had a different signals in your locality. When the numbering system for basically the A while ago I measured the line signal is "far" off (> ± 30 ppm) same TTL gate, so an FJJ131 = timebase frequency on the Auckland frequency I use the 15 kHz aerial DM8510 = SN7474!! Users demanded amateur TV beacon and found it to be directly into the counter on multiple a rationalised type numbering system. about 312 parts per million (ppm) low. period mode to get better resolution Other improvements gave the H, L, S, On the same day I tried my Tandata (± 0.2 ppm for 7 second multiple period LS, ALS, AS, and F varieties. The Td4000 and found the line timebase to instead of ± 7 ppm for 10-second basic idea has not changed; outputs use be 624 ppm low. Amateurs commonly frequency). a saturated switch to ground and a use the Td4000 to provide test patterns weak pull up, inputs have a weak pull and reports on their television At 6 MHz general-purpose crystals up and a threshold of about 1.5 volts up transmissions. have a calibration tolerance of ± 30 from ground.

Figure 1. Oscillators: Left - Tandata, Right -Teletext.

When the video in TV transmissions is ppm and a temperature stability of ± 50 The first MOSFET ICs appeared in very close to the correct frequency and ppm between -20 and +70oC. At room 1964 and since then they have has the correct number of lines per field o continued to increase in popularity more information can be recovered. temperature, 25 C, I expect these because of their high packing density, The timebase may be locally generated oscillators to be within 30 ppm without small power consumption, and low 2 to lock the display to the received adjustment . The published oscillator cost. In 1983, after a series of signal. This means that during contests, designs for the Tandata Td40003 and improvements, High Speed CMOS reports may be given for signals much the Teletext pattern generator4 are gates began replacing the common closer to the noise floor and thus shown in figure 1. Both designs use LSTTL and offered a turbo charged greater distance for the available two 74LS04 buffers biased into their version of the original 4000 series transmitter power. Digital signal linear region by a 1 kΩ resistor from CMOS. Two types are produced: HCT, processing (DSP) may be used to output to input of each gate and with a LSTTL compatible input; and average a noisy signal to reduce the coupled as an oscillator with the crystal HC, with a CMOS compatible input noise. Video recordings of very weak in the feedback path. The same type of and a threshold of about half supply. In signals are possible with local circuit is widely used in personal 1986 the AC and ACT families with synchronisation. computers. higher speed and power became available. Now the supply voltage and To measure the line timebase frequency Integrated Circuits (IC) were first switching noise are being reduced I use a counter calibrator1 fed noise developed by Texas Instruments in while maintaining speed. free video or a 15 kHz aerial 1958 and by 1965 were being used in inductively coupled to the line computers. IC logic gates quickly The earliest crystal oscillator design I deflection of a TV receiver receiving developed from the Resistor Transistor can find uses two sections of a SN7400 the broadcast being investigated. The Logic (RTL) used in the first solid state quad TTL NAND gate for a frequency counter calibrator has a 10 MHz output computers of the early 60's to Diode calibrator.5 This design uses both input that is measured by a frequency Transistor Logic (DTL). When the to output and input to ground resistors, input diodes were made as a transistor, counter. Normally the counter Rf and Rb in figure 2. The references to calibrator is used to determine the the stored charge was quickly removed this article refer to Texas Instruments frequency counter offset error and may from following transistors providing 'Series 54 Crystal Controlled Oscillator' be used as the timebase for a suitable increased speed for no extra cost. These The Network News, No 102 (Dec. counter. This method gives better than gates are called Transistor Transistor 1966). This looks like the source data ± 0.001 ppm when using TV1, TV2 Logic (TTL) and became available in for designing TTL crystal oscillators. and Sky channels but not TV3, Max, 1964.

Page 42 CQ-TV 185 © 1999 by the BATC This design suffers from unreliable For frequencies up to about 4 MHz a Testing is very important. For a single starting, which is largely a function of resistor is used for Xs to increase the oscillator test for reliable starting at the the two bias resistors and variation gate output resistance and reduce the highest expected temperature and from gate to gate.6 The crystal is drive level to the crystal. The resistor reduced voltage. At high voltage and hammered rather hard which causes value is adjusted to provide between 4 low temperature check for uncontrolled high phase noise and long term drift or overtone operation. For a kit or and 5 volts peak to peak across CL2. At production measure your prototype and possible failure with fragile higher frequencies a capacitor about the crystals. The frequency is trimmed with crystal Rr and increase it with an value of CL is used. Scope the voltage a capacitor in series with parallel external series resistor to about 10% across C and C - if these are not a resonant crystals. Series resonant L1 L2 above the manufacturers R max figure smooth sine wave then instability is r crystals will be more or less on then conduct starting tests. frequency without a capacitor. Power possible. supply bypassing is essential - a 10nF The ARRL has published 'The capacitor directly between the IC If you have to use LS gates I have Amateur's Code' for many years: 'The power pins. found R = 10 kΩ and R = 4.7 kΩ f b Radio Amateur is: ... Progressive with works well. Xs is selected to give a knowledge abreast of science, a well- When the supply voltage increases peak to peak voltage of 2 to 3 volts and built and efficient station and operation slowly noise within the linear amplifier is a capacitor above about 8 MHz. above reproach. ... - Paul M. Segal, starts the oscillations. When the supply W9EEA, 1928.' voltage rises quickly, with the CMOS For an economy 4 MHz crystal with a logic gate in figure 2, Rf and CL2 form specified load capacitance (CL) of 30pF We should keep this notion in mind a delay from power application. When and maximum resonance resistance when we design or re-engineer kits. In the gate threshold voltage is reached (R ) of 75Ω. (These values are obtained particular we should change digital the output voltage begins a high to low r circuits towards the new families for from the crystal maker or estimated transition. This is like the initial push the benefits they offer - lower power from statistical analysis of a measured you give yourself on a swing. The consumption, greater tolerance to sample of crystals). amplifier gain overcomes the losses supply voltage variation, greater noise immunity, and lower noise radiation. Many IC manufactures have already or are planning to stop making the old logic families, so, new parts offer a much longer kit production life as well.

References: 1. Jim Rowe. 'Low Cost TV-Derived Frequency Reference'. ELECTRONICS Australia, October 1993, pg 58 ff & November 1993, pg 58 ff. 2. 'RAKON Quartz Crystals Product Figure 2, Improved oscillator design, see text for details. Guide'. c 1989. 3. 'Tandata Service Manual, LC2 and the oscillation builds up until CL1 = CL2 = 2CL less strays = 56pF. Series'. Fisher & Paykel, December clipping reduces the loop gain to unity. 1985. If frequency adjustment is required the 4. Trevor Brown, G8CJS. 'Teletext The most detailed account I have seen trimmer capacitor should have a Pattern Generator'. The ATV of logic gate crystal oscillator design is maximum value of about 30% of CL2. Compendium, ed. Mike Wooding, 7 an RCA application note. This In the above example a 2 to 22pF G6IQM, British Amateur Television application note begins by stating the trimmer would be used with a 47pF Club, March 1989, pg 25 ff. Barkhausen criteria for oscillation then fixed capacitor. 5. D.D.Schmitzer, DJ4BG. 'A Digital gives a mathematical analysis of crystal Calibration-Spectrum Generator'. VHF characteristics and COS/MOS buffers For higher frequency oscillators a coil Communications. November 1971, Pg in linear mode. The Philips Designer's should be used in parallel with C to 196. Guide8 gives some solutions for L1 6. Roger Harrison, VK2ZTB. 'Survey make a tuned circuit at the required instability at higher frequencies where of Crystal Oscillators'. Ham Radio, overtone frequency. the amplifier phase shift is much less March 1976, pg 17 & 18. than 180o. 7. S.S.Eaton. Application Note ICAN- More detailed design would adjust the 6539 'Micropower Crystal-Controlled ratio of C and C to match the gain The Pierce oscillator shown in figure 2 L1 L2 Oscillator Design Using RCA is a recommended replacement for of the amplifier, and adjust Xs COS/MOS Inverters'. Digital those in figure 1. For 4000, HC and depending on the maximum value of Rr Integrated Circuits - , RCA 1971. 8. Philips Electronic Components. HCT series CMOS gates Rf is between for the crystal. These calculations are 1 MΩ and 10 MΩ and R is not used. beyond the scope of this article. 'Crystal Oscillators'. Designer's Guide - b High-speed CMOS. Jan 1986, pg 113.

By Trevor Brown

The BATC was founded in 1949 by Mike Barlow and CQ-TV No. 1 was subsequently printed. Now we are in 1999 it means that we have been in existence for half a century, and in order to commemorate this special occasion we will be holding a rather unique event, Shuttleworth 99. This will be on Sunday 8th August 1999 at Shuttleworth College part of Cranfield University Nr.Bedford. ( remember the venue of CAT 94)

The rear cover of this issue shows a picture of the college venue and inside the front cover is a map of how to get there. All members and guests are welcome. The event will include Lectures and Demonstrations on all topics of Television. Presentations of various awards, and of course the BATC BGM where the accounts for the year will be presented, a committee to run the Club for the next two years will be elected and any other business will be concluded

The Plans for the event are still unfolding, and I hope we can all make this an event to remember. If you have any different ideas, be it a demonstration, something you would like to discuss, or an award you think we should present then please contact Paul Marshall or myself Trevor Brown as soon as possible.

‘Repeater’ is the premier ATV magazine in Holland.

Repeater is a new ATV magazine published in the Netherlands in Dutch. The 13/24cms TX in this issue is reprinted from Repeater with the kind permission of the Editor Rob Ulrich PE1LBP. I hope we can from time to time bring you other extracts as we do with all the ATV magazines.

Information about ‘Repeater’ magazine can be found on their web site at http://www.euronet.nl/users/rulrich, email: [email protected]

Snail mail:- Gibbon 14, 1704 WH Heerhugowaard, Netherlands.

On October 21st 1998, Grant Dixon was persuaded to climb to the top of the Emly Moor transmitter mast by our illustrious chairman who managed to find the time to take these photos.

Left:- Large CRT display of signal from electronic camera built by Jeremy Jago as exhibited at the BATC Rally Subject is former Association President and web— master) C. Grant Dixon. This is a good example of a high signal/noise 32-line picture.

Above, right:- Doug Pitt dangles a rather creased paper poster before the camera. A rigid caption card with the camera properly focused would have given better results of course. All the same, the legibility is quite good when you consider that the minimum criterion for recognition of a 625 line picture is just four digits (BATC contest rules) (Photos by Jeremy Jago)

Left: A ‘Bob Platts’ designed 70 cms transmitter.

Photos on this page by Grahan Hankins

By George W. Allen, N1BEP power is equal to the RF power applied, thermistor mounts for each frequency which can be compared with the meter of interest. An attempt has been made to evaluate reading. the accuracy of damaged HP 478 thermistor power sensing units. When these units are overpowered beyond a Results Frequency Unit I Unit II DC meas. nominal 10 milliwatts, the resistance of Measurements 10 MHz. 1.84 mw. 1.83 mw. 1.84 mw. the sensing thermistor pair changes and were made at 10 30 MHz 4.205 mw. 4.205 mw. 4.205 mw. the units will no longer balance with MHz, 30 MHz, 1152 MHz 2.0 mw. 2.0 mw. 2.0 mw. the H. P. 432A power meter. The 1152 MHz, 3150 3150 MHz. 7.0 mw. 7.0 mw. 7.0 mw. reference and sensing thermistors form MHz and 10368 10.3 GHz 5.0 mw. 5.0 mw. 5.05 mw. two legs of a d. c. bridge circuit. As can MHz. From 10 be seen from Fig. 1, two thermistors in MHz through each leg of the bridge are in series to 3150 MHz the two power mounts read Conditions make a resistance of about 200ohms almost exactly the same RF power. Cables for these power meters are DC at balance. The sensing thermistors Voltage measurements were taken at almost impossible to find, so a cable are in parallel for RF however, giving a each frequency and the DC power was with connectors was fabricated. The nominal 50ohm RF impedance. When calculated for each unit, and then cable length for each leg of the bridge damaged, the resistance and the RF. compared with the power meter scale was made equal by cutting a length of impedance change somewhat. In two reading. Heavy attenuation was used on 3ªwire electric cord and making sure units tested, this resistance was each RF source to bring the impedance that each leg was the same length. reduced, and adding a series resistor to close to 50ohms the sensing leg of the bridge enabled Some cables may be microphonic on balancing the power meter. This the most sensitive scale of the meter. resistance (Rx) was approximately 10 Comparison Results Since the measurements are DC, this worked to good accuracy. A precision to 15ohms. (Fig.1) The results were surprising since both resistor was used for the Rx resistance, unit I and unit II has been damaged to and accurate voltage measurements the point where no balance could be were made, since the errors in the power calculation will multiply. The value of the series resistance was determined by setting the coarse zero of the 432A power meter (10-turn potentiometer) to midpoint, and zeroing the meter by adjusting the resistor in series with the sensing thermistors. The resulting value of resistance is used for the final fixed resistor.

Conclusions With care damaged thermistor power mounts for the H. P. power meters can be recovered and used with reasonable accuracy. The DC measurement technique is obtained. Checking Power cited in literature for the HP power meters as a means of making The HP 432 meter uses a DC bridge The DC and the comparison measurements beyond the accuracy of which has an open circuit voltage of measurements are very consistent the meter scale. about 7.95 volts d. c. applied to each through 3150 MHz within leg of the thermistor bridge. At balance, measurement accuracy. Above 1152 I’m sorry to say that I made an error in this drops to about 2.45volts DC on MHz the measurements were very my article “Using Damaged each leg and the current is about 10 difficult because of drift and voltage Thermistor Power Mounts” (CQ-TV milliamperes. By measuring the voltage measurements. It was necessary to use 184 page 31). The illustration (bottom across the series resistor (Rx), the a bias reference voltage with a digital view of the mount) and the resistor current can be calculated, and by voltmeter to get reproducible results. It string diagram both have the measuring the voltage across the appears that the main effect with connections "A" and "B" reversed. sensing thermistors, the power can be overpowering the heads may be with Damage to the two units tested caused calculated, (W = I x E.) This power is the RF impedance, which must have the r. f. thermistors to be lowered, measured for zero input power to the changed above 3 GHz. With the DC necessitating a series resistor to sensing element, and again with RF power measurements available, a balance. George Allen, N1BEP. power applied. The difference in DC correction factor can be made to © 1999 by the BATC CQ-TV 185 Page 47 Circuit Notebook No. 66

By John Lawrence GW3JGA receiver on. After that the Standby push between the Standby LED and button will work normally. +5V. Recent editions of Circuit Notebook have covered the modification and use The 1N4148 diode ensures that any 2. Connect the circuit shown in Fig. 1 of the Maspro SRE-90R satellite charge that might be in the capacitor, below in place of R122. receiver for the reception of 24cms upon loss of mains input, will be ATV signals. The main advantages of discharged so that it will work correctly 3. Connect collector of TIL 197 and this receiver are its good sensitivity and upon restoration of power. negative end of 68[F capacitor in the ability to tune the sound section to 6 parallel with Standby On/Off push MHz from the remote control. Modification. button. The receiver, when first switched on, On the front panel circuit board:- comes up in stand-by mode. This is not a problem when using it in the shack, 1. Remove R122 that is connected but it makes it unsuitable for use in an ATV Repeater where mains dropout is likely to occur.

GW3FDZ has provided this modification to overcome the problem Auto Switch-on for and his circuit is shown in Fig. 1. Maspro SRE-90R GW3FDZ explains - After the application of power and the Maspro has loaded itself, the Standby LED comes on. This is now in series with the Opto-coupler that turns on and pulses the standby button through the 68[F capacitor, thus turning the BBS Closure By Brian Kelly, GW6BWX view of the uncertain but distant restart only exist on the BBS backup tapes and date and the ongoing running costs, I CDs. Regrettably, the club BBS has had to have decided to close the UUCP close down. It has been out of action mailbox accounts and call it a day. I I would like to thank all those members for a year now, since BT withdrew the have the complete BBS software and and other BBS users who supported me telephone service. Since then all the database backed up on CDs in case the throughout my fight with BT, accounts and mailboxes have been kept situation changes favourably but I think unfortunately they won. It’s a sad fact intact despite the £20.00 a month this is quite unlikely. I can only offer of life that little fishes like me don’t charge for doing so. It was expected apologies to those members who used stand a chance against big sharks like that CableTel would have provided the BBS regularly, I know that in BT! new telephone lines by now but their excess of 7,000 e-mail messages were lost when the mailboxes were deleted. Brian Kelly. GW6BWX, (ex) SysOp of latest estimate for reaching Betwixt BetWiXt BBS. Mansions is "not for at least 12 Many of the ATV files have been made months", a date that slips further into available on the BATC CD but the vast the future each time I call them. In majority of non-ATV related ones now

Intuitive Circuits, LLC is very proud to its memory because all information is products include a "deluxe" id version, announce four new inexpensive on- stored in a non-volatile EEPROM. The RS-232 interface version, and GPS screen display products for Amateur on-board four-button keypad allows version. Television! Here's one of them:- users to program the screen with All products are in stock and ready for up/down/left/right cursor movements. OSD-ID (SA) is a standalone on-screen shipment. For detailed information An on-screen menu allows users to display id board that overlays user including board photo's and screen clear the screen, select the text defined text onto an incoming NTSC shots or to place an order visit our web triggering method, and toggle the video source. The text area consists of a site at http://www.icircuits.com or call translucent mode (a unique feature that 28 column by 11-row character grid. us at 00 1 248-524-1918. We can also allows video to pass through the text Every position on the 28 x 11 screen be reached at [email protected]. We like the major networks do with their (308 characters total) can contain a accept visa and master card. (Products logos). The text triggering method is user-selected character. OSD-ID will also be available through our how, and when, the user defined doesn't require battery backup to retain dealer, P.C. Electronics, very soon). character screen is displayed. $99 Other

By Graham Baker, ZL1TOF chroma reach the same level as white, white, all outputs low represents black, and red and blue reach down to the and any other combination represents a After complaining about the local same level, see figure 1. It is easily colour. I first thought of a system of amateur TV repeater / beacon line possible to broadcast 100% amplitude diodes a bit like the old diode OR gate timebase frequency being 312 ppm off 100% saturated colours, but this is but realised that this was a bit frequency I got the job to put it right. uncommon. complicated. Fortunately the TV repeater was built in modules most of which have one or In New Zealand, according to NZS The final system is shown in figure 2. more spares. 6605:1988, we use television system B When all the FETs are off, resistors R4 for VHF and G for UHF. New Zealand to R8 and the RGB level setting pots

Figure 1. IRE Values of EBU Colour Bars for Composite PAL Video Signal (75% Amplitude 100% Saturation).

differs from strict characteristics of form a voltage divider providing 1 volt Line Timebase Frequency system B and G in that the sound at the sliders (the RGB output). The I modified the first Teletext pattern carrier is displaced by 5.4996 MHz ± base - emitter junction of Q2 is slightly generator module by putting a 27 pF 0.5 kHz from the vision carrier, and the reverse biased. When any one FET is capacitor in series with the 6 MHz modulation levels are identical to those on, the regulator formed by Q1 and Q2 crystal and returned it to service. Other of system I. It is work was done but that is the subject of sensible to use this another article. The second module was standard for amateur a little more difficult as the oscillator TV. was unstable after a basic modification. So, I replaced the 74ALS04 with a The article2 about 74HCU04 and built a circuit known to the Teletext pattern 1 work reliably. generator is ambiguous about the SAA5050 video 75% Colour outputs. Neither is I was asked to modify the video for absolutely correct - 75% amplitude 100% saturated colour. the Philips data This would then correspond to sheet describes the European Broadcasting Union (EBU) outputs as open colour bar levels used widely for drain. To make 75% testing. Since the Teletext pattern we need to make the generator modules use an MC1377 analogue output linear video encoder, it seemed possible 750mV for coloured to modify the video to the new parts and 1000 mv standard. In a composite video signal for white. It so the EBU colour bars have a special happens that all Figure 2. Teletext 75% Colour Adaptor. characteristic, the yellow and cyan outputs are high for

© 1999 by the BATC CQ-TV 185 Page 49 Figure 3. Teletext paging timer. holds the voltage up to 750mV at the I made a special adapter PCB about 45 retrace, not that there is any output. If two FETs are on, the x 20 mm to fit the 75% colour circuit to interference from the random timers. A regulator works a bit harder to keep the the Teletext pattern generator card. The switch could be installed to select the remaining output just below 750mV. circuit could be made on strip board or paging speed (10 and 20 seconds). A The output resistance of Q2 causes the could be added to a new revision of the 'centre off ' switch provides a page difference. I started with one transistor Teletext card. Whatever you do, keep freeze function but a resistor is required in the regulator, but, this made the the wiring as short as necessary to on the open CMOS input to prevent temperature effect on the 75% level reduce signal degradation and continued counting on noise. This about 8% over the temperature range of interference. would be a good modification for the 0 to 70 °C. next revision of the Teletext card. Adjustment will depend upon the Figure 3 shows the added circuit. The component values have been encoder used. Basically: - chosen so the adjustments will be near the centre of their limited range. I have 1. Set all the pots to the centre of their RFI / EMI Reduction specified 1% metal film resistors but travel. Finally, the Teletext pattern generator any high quality resistors will be card used in our repeater /beacon has satisfactory. The transistors are chosen 2. Adjust RGB pots to give 1 volt peak no provision for high frequency for their similar die size to reduce to peak at the input to the encoder. decoupling at the IC power and ground temperature coefficient. Noise on the 5 pins. This does not appear to be a volt supply finds its way on to the 3. Adjust RV1 to give 750 millivolts problem on this design, but, standard video signal through this circuit but no peak to peak on colours at the input to practice is to fit 10 nF or 100 nF multi more than the original 100% amplitude the encoder. This should be the same layer ceramic capacitors directly design. on all three channels. between the supply pins of each IC. Radio Frequency Interference (RFI) generation and reducing the loop area Paging Timer enclosed by the decoupling capacitor leads and IC internal wiring reduces There have been a number of articles susceptibility. IC sockets just add to the describing ways of adding paging to the loop area. Coupling to the Teletext pattern generator. The first power/ground system is reduced if the uses a thumb-wheel switch to select the capacitor is directly connected to the IC high order address of a large EPROM - pins. I used axial capacitors fitted under good for the shack and as a test the ICs as shown in figure 4. instrument. For beacon use, pages could be programmed with information References about the radio club or whatever just 1. Graham Baker, ZL1TOF. like Teletext. A binary counter used to "Oscillators Using Logic Gates", select the high order address automates SPECTRUM, July 1995. page turning. The first uses a 4040 and 2. Trevor Brown, G8CJS. 'Teletext a 555, a simpler and cheaper version Pattern Generator'. The ATV uses a 4060. Compendium, ed. Mike Wooding, G6IQM, British Amateur Television I discovered two signals in the Teletext Club, March 1989, pg 25 ff. chipset that could be used with a 4020 Note: SPECTRUM is the Auckland Figure 4. IC decoupling. counter to give further cost reduction and page switching on the vertical VHF Group monthly magazine.

First part of a series in the The discrete, nearly constant, parts of reproduction on a screen and magazine TV-AMATEUR of the signal represent the valid loudspeaker. information - the transitory parts carry AGAF (German ATV Club), no information. Sampling the valid Digital transmission technology on written by Prof. Uwe Kraus, signal parts and testing if the level is voice signals has been state of the art DJ8DW above or below one or more thresholds with mobile communications for a long reconstructs the data, without counting time; DAB (digital audio broadcasting) Translation by Klaus Kramer, how far from the threshold the signal is. is being tested by public radio. With [email protected] Interference (noise peaks) just above or television, there are digital below the threshold are suppressed and transmissions on satellite and cable the data signal is regenerated world-wide, and digital modes of Introduction completely. terrestrial broadcast that will remove A lot of radio amateurs have been used the present analogue technology has to digital data transmission with a PC Sampling and thresholding are criteria recently begun. and radio for a long time, such as of the robustness in digital RTTY and Packet Radio. transmissions. On the other hand, with After successful propagation of Packet analogue transmission interference in Radio among amateurs the Digital The two level impulsive data signals the channel cannot be removed, as the Amateur Television (DATV) is the from a digital machine are modulated receiver is unable to distinguish next big challenge. This mode is of onto the radio carrier by amplitude or between wanted signal and noise. course interesting to all who practised frequency or phase or a combination of analogue ATV until now, but essential these. The result is a carrier with few The advantages of digital transmission too for all who are experienced in PR, discrete states. In the receiver the can be used for pure analogue signals with PC and multimedia systems and demodulated signal has corresponding (video and sound). At the transmitter who want to involve in this modern and discrete states accordingly. Because of end there is an A/D conversion and futureful technology. bandwidth reductions necessary in the then a digital modulation onto the RF radio channel, the signal does not carrier; at the receiver end after DATV shows a wide field of activity change rapidly from one state to the reconstruction of the digital signal there for the experimenting OM. This series next but in a slower continuous way. is a D/A conversion and then of articles will try to give an

© 1999 by the BATC CQ-TV 185 Page 51 introduction to the new technology and clear about the goals and about the The amount of wrong decisions then get to concrete circuit proposals. possible difficulties to overcome. compared with the sum of all decisions, The author has been working on DATV the error rate, depends upon the signal- with some others for more than three to-noise ratio and affects the received years now; in the autumn of 1995 the Targets for DATV: signal quality. Digital technology first still pictures were transmitted on • distinctive smaller bandwidth provides error correction coding that is the 70 cm band with 1.5Mbit/s over a not possible with analogue technology. 50 km distance. Some weeks ago we • wider range with the same RF To the wanted signal data stream are succeeded in transmitting digital test power and the same picture quality added some correction data derived signals with 2Mbit/s on the 70 cm band from the wanted data. This increases • with 15 Watt RF power into a 15 dB robust on channel interference the overall data rate and the required antenna over a 100 km distance. The RF bandwidth, but it makes possible • spectrum shaping for minimal quality of the regenerated data signals for the receiver to detect and correct interference to other modes made us hopeful of being able to errors for the most part. transmit digital video signals too. • combination with other digital modes ( i.e. high speed PR) Digital modulation on the RF carrier On September 9th 1998 Prof. Uwe There are different procedures to be • combination with modern Kraus, DJ8DW, and his team explained later and examined for their multimedia technologies succeeded in firstly transmitting usefulness for DATV. moving colour pictures with sound via a digital amateur television link over a distance of 100 km with 2MHz New key technologies Channel correction. bandwidth on 434MHz. The transmitter Data reduction on video and sound Multipath reception causes distortion at the Bergische Universitaet in signals by reflections from mountains and Wuppertal (near Cologne) sent 44 Digitising of video and sound signals buildings and leads to overlays of seconds of a car race from Video-CD in gives a data stream that needs differently timed signals at the MPEG-1 using GMSK modulation via considerably more channel bandwidth receiving antenna. With analogue directional antennas to Someren in the on direct transmission than analogue transmission ghosting (double images) Netherlands. There at the home QTH of signals. Modern data reduction would appear, with digital transmission DJ8DW the signal was received clearly technologies make it possible to reduce the received sum signal would be in spite of rain on the way and was digital data to such an amount that the rendered useless without correction saved on hard disk (about 10 Mbytes); required bandwidth is far narrower than efforts. The channel correction circuit software decoding of MPEG-1 video the original analogue bandwidth with contains a digital filter that optimises and sound is possible under Windows similar or even better picture quality. its transfer characteristic automatically 95/98. Very high reduction factors give a loss and cancels the signal distortions. In in quality, of course. World-wide many cases “training sequences” are Analogue ATV transmission standards for moving pictures are added to the transmitted signal, which MPEG-1 and MPEG-2. MPEG-1 gives are known to the receiver. Comparing On the 70 cm band vestigial side band the well-known Video-CD quality with the received distorted sequence to the AM is used with an RF bandwidth of a 1.5Mbit/s data stream that is really nominal sequence the receiver is able to up to 7 MHz, so the band is nearly sufficient for DATV, at the start at adjust the correction filter in the best filled up. As some other modes with least. MPEG-2 is used for higher possible way and react to the varying equal rights are located there, this huge quality television broadcast facilities. conditions. bandwidth mode has no future here. On 23 cm and up, frequency modulation is There are hardware used with a channel bandwidth of about modules for real-time data 20 MHz, with similar considerations reduction in MPEG-1 valid to 70 cm. which are put into the parallel port of a PC and The advantage of analogue ATV is that are able to process PAL it is based on familiar and reliable video signals from a technology and is simple to start. The normal analogue source. In disadvantage lies in the big bandwidth, the future it would be the high RF signal-to-noise ratio desirable to have a solution needed, the signal is susceptible to without a PC. interference with low RF levels, and distorted signals cannot be regenerated. At multi-hop services (repeaters) the Error correction noise is multiplied. coding If the threshold in the DATV digital decoder of the receiver is crossed Before involvement in any new irregularly by a noise peak technology it seems advisable to be we get a wrong decision.

By Don Miller, W9NTP

The rewards of success are now a reality for a group of Experimental Amateur Radio Operators and are currently being shared around the world!

Almost 2 years ago an idea was discussed among Don Miller, W9NTP, Farrell Winder, W8ZCF, Hank Cantrell, W4HTB, Dave Larsen, N6CO and Miles Mann, WF1F, about the possibility of putting a small, lightweight Amateur Radio SSTV System aboard the Mir Space Station. On Saturday, Dec 12, 1998 exciting rewards were received after obtaining, assembling and getting the equipment aboard Mir. Beginning around 17:25 UTC a series of perfect pictures were on 145.985 MHz FM, being shared Robot 36, pictures every 2 minutes, recorded, 3 of which are shown here: with the Mir PMS frequency. At the with the possibility of 720 pictures/day. conclusion of tests, the frequency set The 1st picture shows Cosmonaut aside for SSTV from Mir is 437.975 Earth Stations should now be able to Gennady Padalka (Flight Engineer MHz(+/- Doppler). SSTV Mode is become closely aquainted with the Mir aboard Mir) with the SSTV equipment Space Station and share in the in the background. This equipment was excitement of receiving pictures from sponsored by Tasco Electronics, Outer Space. Schools who schedule Kenwood Corp, PictureTel Corp, Apple contacts with Mir will especially Computer, and assembled by W9NTP, benefit in educational aspects by being W8ZCF and W4HTB . able to see who is actually speaking to them. The 2nd picture shows both Flight Engineer Gennady Padalka and Left: picture 1, above: picture 2. Commander Sergej Andeyev aboard Mir in front of the camera.

The last shot is a typical picture being received from the Piroda Module showing a part of Mir and the Earth in the background. A very detailed history and narrative of the evolution and progress of this story can be found at the MAREX(NA) web at: http://www.geocities.c om/CapeCanaveral/Ha ngar/7355/sstv_proj.ht m

Initial tests were set up

Please send all correspondence for Post and News to the CQ-TV Editor. Ian New websites (from Andy Pawson, 14 Lilac Avenue, Leicester, Emmerson LE5 1FN, England. A superb history of early broadcast video technology can be found at the Tel: 0116 276 9425. address http://www.dmg.co.uk/ibex/museum/ E-mail [email protected] Contents include Magnetic Recording Members sales and wants should be Development Prior to 1956, VERA: An sent to the editor at the above address. Experimental Broadcast VTR, The Development of Ampex Quadruplex Trade adverts should be sent to the and Helical Scan: the Early Years. advertising manager, Steve Ostler (of Radiocraft and Retrovisor fame) now has a website. Chris Smith, and will be carried aloft by a 3000 Clicking on. gram balloon (which may reach as high http://www.users.globalnet.co.uk/~vyte E-mail [email protected] as 120,000 feet. k/vintage%20television.htm will take you to a superbly illustrated treatment Dear Ian, of vintage television and don't forget to Onboard: click on the 'More Info' button as well. I have just put up a new ATV repeater 426.25 MHz ATV (horizontal) here just north of Brisbane in Australia I have just redone the LIST of ATV'ers KE4ROC callsign - you'll see stars, 1250 FM input and 426.250 VSB located at:- meteors and his callsign overlay output We have 50watts output into 2 periodically horizontally polarised folded dipoles http://www.stevens.com/atvq and works extremely well considering. 144.39 MHz APRS packet GPS - also I am some 50km from the site and can check out http://www.aprs.net for live It is now in PDF format and contains get it P5 and most ppl within 50km can tracking or your usual web site or on air ATV'ers from all over the world, not get it at that level. We are currently APRS frequencies. making 2 of the 4 bay 1250 panel just the USA. The file is large, 577K, so will take a little download time. antennas in the BATC book #182 to be 28.322 MHz (or 28.800 MHz) CW....a used as the receive antennas as we Make sure to turn on BOOKMARKS after you have the file on your screen, series of fast continual beeps to track really only have about a 180 deg look on... angle from the site and only about as you can jump to any country or state 20km straight out at 90 deg to cover so by clicking on a bookmark. If NOTE: if you are close in, you can use we hope to get enough off the side of ANYONE wants his or her name not the 5th harmonic of the 10 meter signal the 2 panels to cover most ppl here. published, make sure you tell me and I to track into the balloon payload...either The repeaters callsign is VK4RKC will take it off. It goes if you want it on and it is not or if there are any errors. 141.61 MHz (for 28.322) or 144.000 (for 28.800). There will be a web site Regards, Mark Kyle, VK4KZK Thanks for everyone’s support! It's great working with such a great bunch offered through the Marshall NASA of people! Gene Harlan - WB9MMM, pages that I'll email to you before the From the Internet ATVQ magazine. flight. it will show the digitized images coming down from the balloon. While surfing the web earlier tonight I came across a fantastic new TV and Lift off time is 2:30 AM EST early in Just look what our American the wee hours of Tuesday morning, FM DX site from Finland. It can be Nov 17th. Flight duration will be about found at; http://www.sci.fi/~bkl/ and neighbours get up to (and who said that 70cm ATV was dead?)... 3 hours....landing expected around 5 or yes there's loads of European tv logos, 5:30am EST. Preliminary landing site testcards etc on it! ... and another one, prediction: 40 miles north of Atlanta. this time from the Netherlands. This This is to alert you all to a balloon flight that will be flown to look at the one's at 73s de Bill WB8ELK http://www.cybercomm.nl/~hpl/index.h Leonid Meteor Storm that will be tm and not only features a Test Card happening on November 17th. As a Gallery but also lots of result it will be an unusual NIGHT Contributions transmitter/frequency lists and links. flight....or rather a "wee hour of the morning flight". There will be an light If you have any snippets of news or intensified camera onboard to look at information, then please send them in the meteor trails from the stratosphere to my the editor either by snail mail or email

Page 54 CQ-TV 185 © 1999 by the BATC Non trade advertisements are placed in this column free of charge to paid up members only. Please quote your membership number. Copy should be sent to:- Chris Smith (G1FEF) 25 Dando Close, Wollaston, Northants, NN29 7QB e-mail: [email protected]

Members adverts

Free To anyone, a Heathkit O-12-U golfball! Also an Advance OS2200A going. Could possibly deliver if not too oscilloscope including build storage oscilloscope with instruction far from Eltham in S.E. London. specification and circuits. When last manual and circuits. This unit is faulty Stephen McGuigan G8MFI E-Mail: powered up the spot was the size of a and will need a bit of work to get [email protected]

For Sale BBC ENGINEERING 1922-1972. Thomas. 1977. Ilustrated account of the ATV-7010 ten watt Vestigial sideband Edward Pawley. BBC Books 1972. authors broadcasting life at the BBC, Vision transmitter with 6.0Mhz fm Rare item. Fully illustrated and Pathe and ABCtv up at Didsbury! d/w. sound channel. (Uses low level comprehensive history of BBC £3 All items in VGC. Postage modulation for sound and vision.) engineering produced for the BBCs minimum £1. Contact Dicky Howett. Microwave Modules MML 432/100 50th birthday. Complete with dust 01245 441811. Email: linear 100 watt amplifier. jacket. Ex-college library copy. VGC [email protected] R.N.Electronics inline masthead GaAs £30 BBC YEAR BOOK 1946. Scruffy FET Pre-Amplifier. Microwave d/w. VGC £5 BBC HANDBOOK Modules up converter from 70cms to 1958. d/w. Clean copy £5 Channel 37 UHF TV band. Two, TELEVISION ENGINEERING. twenty one element Tonna 70cms Amos/Birkinshaw. Vol 1. 1953 £5 antennas. One thirteen element 70cms TELEVISION ENGINEERING JVC GRS707 S-VHS-C camcorder, antenna. £299.00. Buyer collects. Amos/Birkinshaw. Vol 2. 1956 £5 auto & manual everything, complete Contact Derek Whitehead, GW3FDZ TELEVISION ENGINEERING with 4 batteries, discharger, and hard on 01 341 247343 after 6.00PM or Amos/Birkinshaw. Vol 3. 1957 £5 case. £500 Olympus VX-303 camera, Email [email protected] BBC V PRESENTS. A Fiftieth with separate VHS recorder (12v), and anniversary celebration. Nicholas separate tuner. £115 (ish) Merlin vision Moss.1986. Lavish glossy picture book mixer, 2 built-in frame-stores, needs of BBCTV history. £5. TECHNIQUES attention. £150 Panasonic Character OF TELEVISION PRODUCTION. Generator VW-CG1E, designed to Rudy Bretz. McGraw-Hill. 1953. 1st mount on a camcorder and connects JVC GC-3300E colour camera with ed. Swimming in tv production between the viewfinder and camcorder zoom lens and Power supply unit. pictures/studios/cameras/ob itself, also has BNC in & outs. £15 Complete, but faulty (EHT?). No vans/transmitters/you name it! No d/w. Marconi picture/waveform monitor, investigation of fault or attempt to £8. TELEVISION PRODUCTION Big and Old, £1. Buyer collects! repair, since fault developed. Boxed. HANDBOOK. Herbert Zettl. 2nd ed Contact Jeremy Power G1WVK Free to anyone who waould like to pick 1968. This American book on tv is (01442) 384716. E-Mail it up or pay carriage. Contact Colin absolutely dripping with pictures of [email protected] Redwood, G6MXL. Tel 01202 665284 cameras, pedestals, lenses, or Email [email protected] microphones, vt machines. 541 pp. Virtually mint interior. No d/w. £8 ITV colour tv development. Scarce. £8 SEE IT HAPPEN. Making of ITN. G.COX.. Fascinating account of the start of ITN. Complete fully operational 70cms ATV Illustrated. d/w. £5 WITH AN system consisting of:- VHF Comm JVC 707 Camcorder King of S-VHS INDEPENDENT AIR. Howard © 1999 by the BATC CQ-TV 185 Page 55 complete with accessories and three offers. 1086-1087. All in excellent condition, batteries - immaculate. All functions most of them completely unused. manual or auto (including time lapse!). Sensible offers please for the complete I have two on offer with instruction set. Regret that we cannot split the set. books (one is boxed) £425 or £750 for Contact Dave Edwards, G8NEO on the pair. Ideal for studio cameras. 01263 513640 (tel / fax) anytime. Panasonic VMX50 video/audio mixer Radio and Television Servicing (boxed with manual)- brilliant £1500 manuals published by MacDonalds. Contact Keith Friday on 01203 Complete set from volume 1 to volume 502500 after 6:30 open to sensible Wanted Wanted: ZNA234E, contact Peter Circuit/manual for ACE PAL CODER. Waugh on 01691 718597 (single large PCB in deep 1U rack). Chris, G8GHH. 01843 224700. Eves. Or Email [email protected] Service manuals for a Panasonic WJ 5500W/B special effects generator and a JVC JX-SV77 video editting Collector of CCD imager IC's would processor. Please contact Phil Marrison like to obtain obsolete or dead CCD's on 01283 790747 (phone / fax) if you for small collection. Anyone else can help. WANTED: Canon EP-3 audio interested in collecting these?, please connectors (same size as EP-4 mains contact me: - Robert Norris, 01252- connector but with three pins), four 674941 male and four female for cable (not Emali:[email protected] chassis) mounting. Also two Pye/Power Controls connectors (four I collect calculators - If you have any female contacts in cast aluminium old calculators, any type - any 'Toblerone' housing). Andy Emmerson condition, working or not. Manuals, G8PTH, 71 Falcutt Way, books about calculators, etc. Please get Northampton, NN2 8PH. Telephone 10 GHz transverter suitable for in touch: Anthony King Tel: 0161 231 01604-844130. upconverting a 145 MHz FM TV IF to 2024 10 GHz. Exact input frquency not critical but output must be crystal controlled. Contact Ian Bennett G6TVJ Tel 0117 9793883 E-mail [email protected] Can anybody tell me the equivalent UK STOP! Before you throw away that old Panasonic model number of a (15-20yrs) Sony Trinitron RX/Monitor, continental VCR N9003T? It is the hi-fi please check and see if it has an IC version fitted with 220V transformer marked "Sony 104A" in it. It has 18 and two-pin mains plug. I wish to pins and a heatsink tab at one end, and replace the head but the part number is Used (but not TOO much) U-Matic is the sync sep/line/frame osc etc. I partially rubbed away and head tapes for portable Sony VO 4800 etc. need one! Also wanted please, Gen- suppliers and National Panasonic do Contact Dicky Howett 01245 441811. lock adapter type AD36E for Panasonic not know which model it could be. Email: [email protected] F10 camera. Valves:- type Contact Brian Theedom, G8LYW, 83 ECL85/6GV6, and E810F / 7788 for Caulfield Road, Shoeburyness,Essex, my Tektronics monitorscope. SS3 9LP. Index of Advertisers

9GHz DRO pucks...... 38 BATC the CD...... 38 Caladan Communications...... 21 GB3XT Kits and Bits...... 7 HS Publications...... 52 PC-ATV - The Arcade Shop...... 6 Severnside Television Group...... 29 VHF Communications...... 29 Worthing & District Video Repeater Group...... 41

Printed by Cramphorn Colour Printers Ltd., 15c Paynes Lane, Rugby, CV21 2UH, England. Telephone: 01788 577781.